Matthew Hennessey

Chainguard received PHP’s fix for two critical RCEs under embargo, like every other distributor. On October 21 at 07:41 UTC, more than six hours before the coordinated release, it published built images containing that fix. The PHP Foundation’s postmortem says Chainguard unilaterally broke the embargo. From that point, any attacker could study the fix in binary form while every other PHP user was still waiting. CVE-2026-109618 and CVE-2026-109619 let attackers run code on web servers without logging in. PHP runs 69% of websites whose server-side language is known. The embargo was already under strain. The CVE IDs leaked the day before, and Calif accidentally posted an exploit video that evening. PHP pulled the release forward a day but held it until 14:00 UTC, because distributors were still packaging and an immediate release would have left many users without a clean way to update. Chainguard went first anyway. Chainguard CEO Dan Lorenc says several vendors in the disclosure had reported exploits in the wild, and that he notified the group right after making the call. He did not name the vendors or publish evidence. PHP’s security team found no working public exploit by release time. Lorenc has since apologized for the added stress on PHP’s maintainers. Chainguard’s disclosure policy allows it to shorten timelines when exploitation is active. The patch it shipped was PHP’s, shared under PHP’s embargo. In July, Lorenc wrote: “Pre-disclosure protection extends exactly as far as the people you can vet and hold to an embargo.” Coordinated disclosure only works if everyone holding the fix ships at the same moment. When one party goes early, the fix becomes a map for attackers, and the users still waiting carry the risk. PHP owned its part. Its postmortem calls the long delay in fixing the underlying bug, first spotted in a 2024 audit, “a structural failure.” It is asking the companies that run on PHP to fund more engine engineers. If you haven’t patched: update the PHP runtime itself, not just WordPress or your framework, to 8.5.12, 8.4.27, 8.3.36, or 8.2.35. Then restart your workers.