Rewrote the exploit to correctly avoid GET requests between OOM
trigger and crash verification (RINIT zeros BG state on every
request). Filler field spray (100 x 8200B = 300 pages) reliably
reclaims the stale struct pages. Crash confirmed on first attempt.
Updated README and FINDINGS to accurately describe:
- The 8216-byte struct (3 pages), not the earlier 64-byte bin
- GC header overlap that blocks controlled RCE (offsets 0-23)
- Three independent patch layers in PHP 8.3.36/8.4.27/8.5.12
- Honest exploitation status: UAF crash confirmed, RCE not achieved
The original exploit put the file upload before the field flood,
so the progress handler's serialize completed before OOM fired.
This meant BG(serialize) was not left stale.
The corrected flow:
Phase 1: Create ~500KB session file via large upload progress value
Phase 2: Fill memory with fields, then file upload triggers session
re-init which OOMs during unserialize of the large session
Phase 3: Verify stale BG(unserialize) state on the surviving worker
Confirmed on PHP 8.3.6, Apache 2.4.58: error log shows
"tried to allocate 503808 bytes" during session handling,
followed by "Session ini settings cannot be changed when a
session is active" on subsequent requests.
Pure memory corruption path: OOM during multipart parsing leaves stale
BG(serialize) state in Apache mod_php prefork workers. Heap spray
reclaims the freed 64-byte slot, giving control of a HashTable's
pDestructor for arbitrary function call.
No LFI, no framework, no non-default PHP settings required.
Tested on PHP 8.3.6 + Apache 2.4.58 (prefork MPM). Confirmed:
- OOM via field flood, worker survival, session file persistence
- Stale BG(serialize).level across requests
- Heap spray targeting ZendMM 64-byte bin
New exploit at fcgi/exploit_fcgi.py combines the session upload progress
write primitive (CVE-2026-109618/109619) with direct FastCGI access to
PHP-FPM. A slow-drip multipart upload holds one FPM worker in the
multipart parser while a second FastCGI request includes the poisoned
session file via auto_prepend_file.
Works on default PHP configuration, no LFI, no framework, no libraries.
security.limit_extensions does not block auto_prepend_file inclusion.
php_admin_value in pool config does not block PHP_VALUE from raw FastCGI.
Tested and confirmed RCE on:
PHP 8.3.6 (local, pre-patch)
PHP 8.3.35 (Docker, pre-patch)
PHP 8.3.36 (Docker, patched)
PHP 8.4.27 (Docker, patched)
Mitigated by session.upload_progress.enabled=0 or blocking FPM access.
Also includes nolfi/ exploit (served save_path + pathinfo routing) from
previous work, and updated README with mitigation matrix for all vectors.
Exploits the interaction between php_serialize and php session handlers:
when one endpoint writes sessions with php_serialize (Laravel, Symfony
default) and another reads with the php handler (PHP default), injected
pipe characters cause arbitrary deserialization at session_start().
12 built-in POP chains covering current and legacy library versions:
- monolog3-fw: Monolog 3.0+ (tested 3.12.1, latest)
- laravel10-cmd/fw: illuminate 10.0-13.x+ (tested v13.38.0, latest)
- monolog-cmd/fw: Monolog 1.17.2-2.x
- laravel-cmd/fw: illuminate 5.4-8.x
- guzzle-fw: Guzzle 4.0-7.x
- symfony-cmd/fw: Symfony 2.6-4.4.18
- wordpress-cmd/fw: WordPress 6.4.0-6.4.1
All chains tested end-to-end through the full HTTP exploit flow on
PHP 8.3. Accepts custom phpggc chains via --chain-file.
neko