CVE-2026-109618
RCE via OOM corruption
What happened?
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).
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| php-srcPHP Group | affected: 8.2.* to < 8.2.35; affected: 8.3.* to < 8.3.36; affected: 8.4.* to < 8.4.27; affected: 8.5.* to < 8.5.12 | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
CISA lists this CVE in its Known Exploited Vulnerabilities catalogue. Added 2026-10-26.
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.
Sources and remediation references
- https://www.cve.org/CVERecord?id=CVE-2026-109618
- https://github.com/php/php-src/security/advisories/GHSA-w8hw-w9fx-j79w
- https://www.wiz.io/blog/php2shell-php-rce
- https://arcticwolf.com/resources/blog/php2shell-critical-php-vulnerabilities-enable-unauthenticated-remote-code-execution/
- https://php2shell.delftintellab.com
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-109618
- http://www.openwall.com/lists/oss-security/2026/10/21/6
- http://www.openwall.com/lists/oss-security/2026/10/23/5
- http://seclists.org/fulldisclosure/2026/Oct/51
- https://cert-portal.siemens.com/productcert/html/ssa-566512.html
- https://cert-portal.siemens.com/productcert/html/ssa-566435.html
- https://cert-portal.siemens.com/productcert/html/ssa-166980.html