# Briefing for a security researcher: What are the bug classes, what was demonstrated, and what is still open?

The php2shell story for a security researcher: what to decide, the claims it rests on with their status and sources, and what is still open.

Briefing · Security researcher · from the same 70 claims, selected and ordered for one reader

# What are the bug classes, what was demonstrated, and what is still open?

Bug classes, what was demonstrated against what, credits, and the open technical questions.

## What to decide or do
- Two classes: OOM longjmp leaving request memory uninitialised (CWE-416/755/824/1325/1419), and worker global state pointing at freed request memory across requests.
- mod_php exploited pre-application with default limits; FPM via session upload progress for 109619; FPM for 109618 disputed between the GHSA and the Foundation blog.
- Credits on both GHSAs: lcfr-hax, sagitzadik-wiz, amyb-oai, tomash-areion. The last is unexplained.
- Open: the Fediverse report of a third bug or incomplete fix; Calif's hash pre-image; whether the embedded demo is the deleted video.
- The fix changes the engine: soft OOM at a VM safe point, hard OOM via _exit(). Expect behavioural differences under memory pressure.

## The facts this rests on
- confirmed two or more primary sources agree, or the fact was counted from a captured file
- reported one party says so, and it has not been contradicted
- disputed the sources disagree, and both readings are shown
- contradicted a primary source says otherwise
- unverified even the reporting outlet could not check it
- p/n primary sources among the n cited; a blocked capture is counted and marked

| Claim | Who says it | Status | Primary | Sources |
|---|---|---|---|---|
| Two critical vulnerabilities, CVE-2026-109618 and CVE-2026-109619, each CVSS v4.0 9.2, fixed in PHP 8.5.12, 8.4.27, 8.3.36 and 8.2.35 | PHP Group (CNA), GitHub advisories, php.net | confirmed | 5/5 | [CVE record](../../sources/cve-cve-2026-109618/index.html) [CVE record](../../sources/cve-cve-2026-109619/index.html) [PHP](../../sources/github-ghsa-w8hw-w9fx-j79w/index.html) [PHP](../../sources/github-ghsa-6wmf-4rv5-p3rp/index.html) [php.net](../../sources/php-net-advisory/index.html) |
| Unauthenticated RCE over HTTP against Apache mod_php with default settings, before any application code runs | PHP security team (GHSA, oss-security), php.net | confirmed | 3/3 | [PHP](../../sources/github-ghsa-w8hw-w9fx-j79w/index.html) [oss-security](../../sources/openwall-oss-security-2026-10-21-6/index.html) [php.net](../../sources/php-net-advisory/index.html) |
| The fix removes longjmp() for out-of-memory errors in favour of a delayed soft OOM at the next VM safe point and a hard OOM via _exit(); the changelog line is 'Avoid state corruption via bailout' | PHP security team | confirmed | 3/3 | [PHP](../../sources/github-ghsa-w8hw-w9fx-j79w/index.html) [php.net](../../sources/php-net-changelog-8/index.html) [php-src](../../sources/github-php-src-branch-7.4-backport/index.html) |
| Updating is the only complete mitigation; the configuration measures reduce exposure to specific paths and do not make an installation safe | php.net; PHP security team | confirmed | 3/3 | [php.net](../../sources/php-net-advisory/index.html) [oss-security](../../sources/openwall-oss-security-2026-10-21-7/index.html) [PHP](../../sources/github-ghsa-6wmf-4rv5-p3rp/index.html) |
| Triggering the bug is much easier than turning it into code execution; the CVSS vector says attack complexity highFastly: 'most deployments may be safe from RCE. Do not assume this holds true for you.' Imperva: five demonstrated techniques, three via session upload progress; about 67 KB of memory disclosed per attack. | Imperva; Fastly; the CVE record | confirmed | 3/3 | [Imperva Threat Research](../../sources/imperva-blog-php2shell/index.html) [Fastly](../../sources/fastly-blog-php2shell/index.html) [CVE record](../../sources/cve-cve-2026-109618/index.html) |
| Both bugs are in the C engine, not in PHP code: the allocator's longjmp-based bailout on out-of-memory, and request globals that survive a failed requestThe fix replaces bailout with a delayed error and an UnwindExit at a safe point, adds a hard limit that _exits, and resets the globals. See the code page. | php/php-src fix commit; the GitHub advisories | confirmed | 3/3 | [php/php-src , read from a clone](../../sources/github-php-src-fix-commit-3584a98bd/index.html) [PHP](../../sources/github-ghsa-w8hw-w9fx-j79w/index.html) [PHP](../../sources/github-ghsa-6wmf-4rv5-p3rp/index.html) |
| Pre-authentication RCE was confirmed against WordPress, Drupal, Joomla, MediaWiki, Roundcube, Magento, phpMyAdmin, Nextcloud, Laravel, Symfony and WHMCSTwo researcher parties, no third-party reproduction in the vault. The demo videos were not downloaded. | Calif; Wiz for WordPress and Drupal | reported | 2/2 | [Calif](../../sources/calif-php2shell/index.html) [Wiz](../../sources/wiz-blog-php2shell/index.html) |
| None of the public proof-of-concept exploits reviewed by VulnCheck has the correct mechanism; a lab reproduction of the leaked PoC's precondition produced a clean 200The Hacker News says the same of the public code. Fastly: working RCE needs knowledge of the running binary's layout on x86_64. | rjmendez (detection author) citing VulnCheck; Huntress | reported | 1/2 | [rjmendez, GitHub](../../sources/github-rjmendez-phpup-2026/index.html) [Huntress](../../sources/huntress-php2shell-rapid-response/index.html) |
| Patching the demonstrated paths does not make the bailout mechanism safe; more paths should be expectedA position, from a vendor; consistent with the Fediverse report of a third bug. | Fastly | reported | 1/2 | [Fastly](../../sources/fastly-blog-php2shell/index.html) [oss-security](../../sources/openwall-oss-security-109619-thread/index.html) |
| Remote code execution is confirmed on PHP-FPMGHSA-w8hw (CVE-2026-109618): 'no complete FPM exploit has been demonstrated for this SAPI'. The Foundation blog: RCE 'was also confirmed on PHP-FPM through application-level code paths'. GHSA-6wmf (CVE-2026-109619): session lifecycle RCE 'validated against mod_php and FPM'. The accounts may refer to different CVEs. | PHP Foundation blog; GHSA-6wmf for the session path | disputed | 4/4 | [PHP Foundation](../../sources/php-foundation-blog-security-release/index.html) [PHP](../../sources/github-ghsa-6wmf-4rv5-p3rp/index.html) [PHP](../../sources/github-ghsa-w8hw-w9fx-j79w/index.html) [oss-security](../../sources/openwall-oss-security-2026-10-21-6/index.html) |
| All PHP versions from 5 onwards are affected by at least one of the flawsThe CVE records list only 8.2 to 8.5 with defaultStatus 'unaffected'. php.net published source backports for 7.4, 8.0 and 8.1, which implies they are affected. A scanner that trusts the CVE record will miss 7.4 to 8.1. | NCSC-NL; Wiz ('>= 5.4'); CERT-FR (5.x, 6.x, 7.x, 8.0, 8.1) | disputed | 3/4 | [NCSC-NL](../../sources/ncsc-nl-advisories/index.html) [Wiz on X](../../sources/x-wiz-io-php2shell/index.html) [CERT-FR](../../sources/certfr-2026-ale-014/index.html) [oss-security](../../sources/openwall-oss-security-109619-thread/index.html) |
| A web application firewall may provide some protection until systems are patchedSwiss BACS: 'Even a web application firewall alone is not sufficient.' Cloudflare says its rules blocked the traffic it saw and that attackers mutated payloads to get past them. | CISA | disputed | 3/3 | [CISA](../../sources/cisa-alert-php-20261021/index.html) [BACS](../../sources/ch-bacs-warnung-php/index.html) [Cloudflare](../../sources/cloudflare-blog-php2shell-waf/index.html) |
| The flaws are CVSS 10.0The PHP Foundation: 'a wrong CVSS score of 10.0 (the actual score is 9.2)'. Daubois traces it to a social post relayed by Phoenix Security and to watchTowr via Cyber Daily. | social posts on 20 October, relayed by a vendor and a news site | contradicted | 1/2 | [PHP Foundation](../../sources/php-foundation-blog-security-release/index.html) [Daubois](../../sources/daubois-blog-php2shell-rumors/index.html) |
| The 8.5.12 fix may be incomplete, or there is a third, different bugPer a Matrix channel, Canonical asked PHP and 'was told that it's unrelated and not a real issue'. Second-hand. Nothing from PHP on the list at capture. | Fediverse posts relayed to oss-security by Aaron Rainbolt and Yves-Alexis Perez | unverified | 0/1 | [oss-security](../../sources/openwall-oss-security-109619-thread/index.html) |
| Calif found the flaws first: discovery 1 August, hash commitment 5 August, report to PHP 11 AugustThe hash tweet is dated 5 August 2026 on X; its pre-image has not been published, so what it commits to cannot be checked. | Calif; PHP Foundation (report date) | confirmed | 3/3 | [Calif](../../sources/calif-php2shell/index.html) [Ryan Austin , Calif on X](../../sources/x-lcfr-hax-hash-tweet/index.html) [PHP Foundation](../../sources/php-foundation-blog-security-release/index.html) |
| The GitHub advisories credit four reporters: lcfr-hax (Calif), sagitzadik-wiz (Wiz), amyb-oai (OpenAI) and tomash-areiontomash-areion is not named in the PHP Foundation's thanks and appears nowhere else on this beat. | GitHub security advisories | confirmed | 2/3 | [PHP](../../sources/github-ghsa-w8hw-w9fx-j79w/index.html) [PHP](../../sources/github-ghsa-6wmf-4rv5-p3rp/index.html) [Daubois](../../sources/daubois-blog-php2shell-rumors/index.html) |
| The out-of-memory issue was found in a 2024 audit by Quarkslab (funded through OSTIF and the Sovereign Tech Agency) but exploitation was not proven, so it was not fixedTwo parties agree. The Foundation calls the delay 'a structural failure'. Cloudflare lists Quarkslab among the 2026 disclosers; nobody else does. | PHP Foundation; Calif | confirmed | 2/2 | [PHP Foundation](../../sources/php-foundation-blog-security-release/index.html) [Calif](../../sources/calif-php2shell/index.html) |
| The flaws were found by researchers using frontier AI under OpenAI's Patch the Planet initiativeAll three research parties say AI was used. Calif: 'No special harness, or access to models that weren't generally available to everyone were used'. Calif does not name a model; Wiz names Gemini 4 Argon, GPT-5.6 Sol and Wiz Atlas; OpenAI's blog reportedly names GPT-5.6 Sol but is blocked. | BBC; OpenAI; Calif; Wiz | reported | 3/4 | [BBC News](../../sources/bbc-live-ckgel5xp2xv9t/index.html) [OpenAI on X](../../sources/x-openai-php2shell/index.html) [Calif](../../sources/calif-php2shell/index.html) [Wiz](../../sources/wiz-blog-php2shell/index.html) |
| OpenAI independently reported the same root cause on 11 August, with further vectors on 18 SeptemberThe GitHub advisories credit amyb-oai among four reporters. OpenAI's own post credits Calif's discovery 'using GPT-5.6 Sol' and Wiz; an X Community Note disputes OpenAI's role. | PHP Foundation | reported | 2/2 | [PHP Foundation](../../sources/php-foundation-blog-security-release/index.html) [PHP](../../sources/github-ghsa-w8hw-w9fx-j79w/index.html) |
| Wiz Research independently discovered the first flaw on 19 August and reported on 24 AugustWiz's X post says 'Wiz Research uncovers' with no credit to Calif or OpenAI; the blog thanks both. | Wiz; PHP Foundation (24 August) | reported | 2/2 | [Wiz](../../sources/wiz-blog-php2shell/index.html) [PHP Foundation](../../sources/php-foundation-blog-security-release/index.html) |
| The most severe flaws ever detected by AIWiz's own wording is 'among the most severe vulnerabilities discovered in PHP, and arguably in software history'. OpenAI: 'one of the most impactful vulnerabilities in recent memory'. | BBC attributing Wiz | reported | 1/2 | [BBC News](../../sources/bbc-live-ckgel5xp2xv9t/index.html) [Wiz](../../sources/wiz-blog-php2shell/index.html) |
| Quarkslab's published audit summary lists 27 findings, two redacted because their fixes were complex and in progress; it does not describe an out-of-memory findingThe Foundation says the OOM signs were found while fixing one of the audit's findings, not in the audit report itself. | Quarkslab's blog; a Substack analysis | reported | 1/2 | [Quarkslab](../../sources/quarkslab-blog-php-src-audit/index.html) [David Lopez-Kurtz](../../sources/substack-lopezkurtz-patch-is-the-exploit/index.html) |
| Chainguard's team found the same bugs independently with an AI harness and a frontier model after a researcher warned them on the Friday beforeUnverified by anyone else. | Dan Lorenc, via The Register | reported | 0/1 | [The Register](../../sources/theregister-php-blames-chainguard/index.html) |
| Frontier AI found the flaw ahead of attackers, giving defenders time to prepareAmazon reports an exploit attempt against a honeypot on 17 October, four days before disclosure, from an actor whose source of exploit information is unknown. | OpenAI | disputed | 1/2 | [OpenAI on X](../../sources/x-openai-php2shell/index.html) [THN](../../sources/thehackernews-php2shell-4days/index.html) |
| The release moved forward from 22 October 14:00 UTC to 21 October 14:00 UTC because of the leakThe php.net ChangeLog still dates all four releases 22 October. Wiz's X thread still says 22 October. | PHP Foundation; php.net pre-announcement; Wiz thread ('Apply the Oct 22 security release') | confirmed | 4/4 | [PHP Foundation](../../sources/php-foundation-blog-security-release/index.html) [oss-security](../../sources/openwall-oss-security-2026-10-20-34/index.html) [Wiz on X](../../sources/x-wiz-io-php2shell/index.html) [php.net](../../sources/php-net-changelog-8/index.html) |
| On 20 October at about 15:00 UTC the two CVE IDs began circulating on forums and social media with a wrong release time and a wrong CVSS score; no technical details leakedPrimary party. The Foundation does not say who or where. | PHP Foundation | reported | 2/2 | [PHP Foundation](../../sources/php-foundation-blog-security-release/index.html) [PHP Foundation](../../sources/phpfoundation-blog-security-release-leak/index.html) |
| The leak started with an anonymous Hacker News post citing a reliable source, which came down after screenshots spread; a screenshot of the 'PHP2Shell tool' credited to Calif.io and a short exploitation video also went up and came downContradicts the Foundation's 'no technical details leaked' and The Hacker News's 'a proof-of-concept exploit leaked'. No copy of the post, screenshot or video is in the vault. | Alexandre Daubois (PHP security team, personal blog) | reported | 0/1 | [Daubois](../../sources/daubois-blog-php2shell-rumors/index.html) |
| watchTowr confirmed in public that the bugs were real and posted both CVE numbers before the release | Daubois; CERT-EU lists a watchTowr X post among public reports | reported | 1/2 | [Daubois](../../sources/daubois-blog-php2shell-rumors/index.html) [CERT-EU](../../sources/certeu-sa-2026-018/index.html) |
| Calif mistakenly published a video around 20:00 UTC on 20 October showing its proof of concept against a number of targets; copies circulated and 'contributed to accelerated development of various PoCs'Calif's own page does not mention a leak or a deleted video; it embeds two demo videos. Whether one of them is the deleted video is unknown. | PHP Foundation | reported | 3/4 | [PHP Foundation](../../sources/php-foundation-blog-security-release/index.html) [PHP Foundation](../../sources/phpfoundation-blog-security-release-leak/index.html) [BBC News](../../sources/bbc-live-ckgel5xp2xv9t/index.html) [Calif](../../sources/calif-php2shell/index.html) |
| Mitigation advice given to a few critical-infrastructure providers from about 23:00 UTC on 20 October may have leaked | PHP Foundation | reported | 1/1 | [PHP Foundation](../../sources/php-foundation-blog-security-release/index.html) |
| Chainguard unilaterally broke the embargo on 21 October at 07:41 UTC by publishing built images containing the fixDan Lorenc (via The Register): 'I made the call to get these out early when exploits hit in the wild'; several unnamed vendors had reported exploits; Chainguard's honeypots trapped IPs; a researcher warned the company on the Friday and its team then found the bugs independently with an AI harness. No evidence published. The PHP security team found no functional exploit by release time. | PHP Foundation; Chainguard's CEO accepts the time and denies leaking | disputed | 1/3 | [PHP Foundation](../../sources/php-foundation-blog-security-release/index.html) [The Register](../../sources/theregister-php-blames-chainguard/index.html) [Feross Aboukhadijeh on X on X](../../sources/x-feross-chainguard/index.html) |

## What is still open
- Who first leaked the CVE IDs on 20 October, and where. The PHP Foundation does not say; a PHP security team member points to an anonymous Hacker News post. No copy of that post is in the vault.
- Whether the deleted Calif video is the one now embedded on Calif's own write-up. Calif's page does not mention the leak.
- Whether any site was actually compromised before it was patched or taken offline. Every claim of exploitation so far is of attempts, probes or honeypot hits.
- Which sites were really taken offline, and why. The BBC's list (parts of Wikipedia, Edinburgh council, French government services, the University of Geneva, the BBC itself) has not been captured from any of those organisations. Latvia's geo-blocking is the one documented case, from the agency itself.
- Whether the 8.5.12 fix is complete. A Fediverse report of a third bug or incomplete fix reached oss-security on 21 October; PHP reportedly told Canonical it is unrelated. Nothing from PHP on the list yet.

The full set of claims is on [every claim](../../claims/index.html); the ordered steps for a vulnerable system are on [if you run PHP](../../playbook/index.html). Other briefings: [Board member or executive](../board/index.html) · [Security lead](../security/index.html) · [PHP or platform engineer](../engineer/index.html) · [Journalist](../journalist/index.html) · [Analyst or advisor](../analyst/index.html) · [CISO](../ciso/index.html) · [CTO](../cto/index.html) · [CFO](../cfo/index.html) · [Head of AppSec](../appsec/index.html) · [Developer](../developer/index.html) · [Media and communications team](../comms/index.html).


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