CVE-2026-109618
CRITICAL severity · CVSS 9.8 · Use-after-free · actively exploited (CISA KEV)
9.8CVSS CRITICAL exploited
Actively exploited in the wild (CISA Known Exploited Vulnerabilities).
Added to KEV 2026-10-26. US federal agencies must patch by 2026-10-29.
What to do: read the PHP “php2shell” RCE (CVE-2026-109618/109619): what to do now — a step-by-step remediation runbook.
Summary
PHP uses longjmp() for out-of-memory (OOM) errors to exit the current context and abort handling of the request. Some contexts may not properly account for this scenario and leave request memory in an uninitialized state before performing an allocation. The subsequent request cleanup procedure may read or branch on this memory. Multiple OOM strategies can consistently trigger this condition and lead to remote code execution (RCE).
Impact & exploitability
Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
Exploit probability (EPSS)100%
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected products we track (2)
Recommendation
This vulnerability is being actively exploited in the wild — patch affected products urgently. Open any affected product above for its exact safe version.
Additional information
- NVD record
- https://github.com/php/php-src/security/advisories/GHSA-w8hw-w9fx-j79wAdvisory
- http://www.openwall.com/lists/oss-security/2026/10/21/6Advisory
- http://www.openwall.com/lists/oss-security/2026/10/23/5Advisory
- https://arcticwolf.com/resources/blog/php2shell-critical-php-vulnerabilities-enable-unauthenticated-remote-code-execution/Advisory
- https://cert-portal.siemens.com/productcert/html/ssa-566512.htmlAdvisory
- https://php2shell.delftintellab.comAdvisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-109618
- https://www.wiz.io/blog/php2shell-php-rceAdvisory