PHP2Shell: Two Unpatched Critical PHP RCE Flaws (CVSS 9.2) Trigger Emergency Security Alert
Oct 21, 2026
Vulnerability / Web Security
This story is developing and was written before PHP's scheduled 14:00 UTC release on October 21. Once the release is out, the affected and fixed versions below are confirmed by the official advisory. PHP will ship an out-of-cycle security release at 14:00 UTC today, October 21, for two critical vulnerabilities that its security team has rated 9.2 on the CVSS v4.0 scale but has not described. ⚡ UPDATE — PHP Issues Emergency Patches for Two Critical PHP2Shell RCE Flaws as Exploit Attempts Emerge Security researchers at watchTowr say the two flaws allow remote code execution. Only the four supported PHP branches, 8.2 through 8.5, can receive the fix, and no exploitation has been reported so far. The advance notice followed a leak. On October 20, a post on HN said two PHP remote code execution flaws, rated CVSS 10.0 and affecting versions from PHP 5 onward, would be disclosed on Thursday, October 22. The poster said they had "no evidence beyond 'source: trus...