CVE-2026-109619: PHP flaw exploited in the wild, what we know

PHP has various global state that temporarily points into request memory. In some scenarios, global state may not be correctly reset, or may be repopulated after being reset. The global state may then refer to request memory even after it has been freed. Subsequent requests may read or branch on this stale state before it is fully initialized. Multiple strategies can trigger this condition and produce remote code execution (RCE).

• Severity: CRITICAL (CVSS 4.0 9.2, vector CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N).
• Weakness: CWE-416, CWE-755, CWE-824, CWE-1325.
• NVD published 2026-10-21, status Analyzed.

Anyone running php in the version ranges below. Internet-facing instances are the priority.

• php php: from 5.4.0 up to (not including) 8.2.35.
• php php: from 8.3.0 up to (not including) 8.3.36.
• php php: from 8.4.0 up to (not including) 8.4.27.
• php php: from 8.5.0 up to (not including) 8.5.12.
• paloaltonetworks pan-os: from 10.2.0 up to (not including) 10.2.7.
• paloaltonetworks pan-os: from 11.1.0 up to (not including) 11.1.4.
• paloaltonetworks pan-os: from 11.2.0 up to (not including) 11.2.4.
• paloaltonetworks pan-os: from 12.1.0 up to (not including) 12.1.4.
• paloaltonetworks pan-os: from 12.2.0 up to (not including) 12.2.4.

Version ranges come from the NVD CPE configuration. Confirm against the vendor advisory before you rely on them.

• Exploited in the wild: added to the CISA Known Exploited Vulnerabilities catalog on 2026-10-26; federal remediation due date 2026-10-29.
• Public proof-of-concept code: 25 GitHub repositories from 25 accounts, the first on 2026-10-21.

CISA added CVE-2026-109619 to its Known Exploited Vulnerabilities catalog on 2026-10-26. A KEV listing means CISA has evidence that attackers are using the flaw against real systems, not just that it could be used.

If your business runs php, put this at the top of the patch list. CISA gave US federal agencies until 2026-10-29 to deal with it, and that is a sensible deadline for a small business too.

• Patch. Update to a fixed release: php php 8.2.35 or later; php php 8.3.36 or later; php php 8.4.27 or later. These versions come from NVD's configuration data, so confirm them against the advisory from php.
• If you cannot patch yet. Follow CISA's required action: 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.
• Check your exposure. Find out whether php can be reached from the internet, for example a VPN portal, an admin login page or a file-transfer site. Your firewall's port-forwarding rules and your IT provider's list of public-facing systems are the quickest places to look. Exposed copies come first.
• When to call IT support. Call your IT support provider now if you run php and cannot confirm it is updated, if it was reachable from the internet before you patched it, or if you notice accounts, sign-ins or files you do not recognise. The last two can mean the system was already hit, and checking that properly takes someone who can read the logs.

• EPSS (probability of exploitation activity in the next 30 days): 100.00%, higher than 100% of all scored CVEs (as of 2026-11-03).
• CVERadar threat level: 91/100 (see methodology).
• Likely ATT&CK techniques: T1203 Exploitation for Client Execution (inferred); T1190 Exploit Public-Facing Application (inferred).

1. Find every instance. List where php runs, including test, DR and forgotten internet-facing systems, and record the installed version.

   php -v

2. Upgrade to a fixed release. php php: 8.2.35 or later; php php: 8.3.36 or later; php php: 8.4.27 or later; php php: 8.5.12 or later. Get the build from the vendor advisory.

   # Debian/Ubuntu
   sudo apt update && sudo apt install --only-upgrade php
   # RHEL/Rocky/Alma/Fedora (package names differ, e.g. httpd, openssh-server, kernel)
   sudo dnf upgrade --refresh

   Distribution packages carry the fix under the distro's own version number; check your distro's security tracker for this CVE.

3. If you can't patch today, follow CISA's required action: 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.
4. Verify the fix. Re-run the version check above on every instance and confirm it reports the fixed build (8.2.35 or later). Re-scan from outside if the service is exposed.
5. Hunt for signs of earlier compromise. If the system was exposed before you patched, assume it may have been hit and check the items below.
6. Rotate credentials stored on or used by the affected system if you cannot rule out compromise, and keep the logs you reviewed.

Detection hints

• T1190 Exploit Public-Facing Application: Review WAF, reverse-proxy and application logs for unusual requests to php (odd paths, oversized or encoded payloads, bursts of errors), going back to at least 2026-10-21.
• T1203 Exploitation for Client Execution: Exploitation of client or server software usually shows as crashes of the affected process followed by unexpected child processes; check EDR alerts for both.

Detection commands are generic starting points, not CVE-specific signatures. Use the indicators from the vendor advisory when it publishes them.

• NVD: CVE-2026-109619 nvd.nist.gov/vuln/detail/CVE-2026-109619
• CVE.org record www.cve.org/CVERecord?id=CVE-2026-109619
• Vendor link from CISA KEV www.php.net/
• Vendor link from CISA KEV www.cisa.gov/news-events/alerts/2026/10/21/critical-vulnerabilities-ph
• Vendor link from CISA KEV www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-up
• Vendor link from CISA KEV www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-
• Mitigation, Vendor Advisory github.com/php/php-src/security/advisories/GHSA-6wmf-4rv5-p3rp
• CISA KEV catalog www.cisa.gov/known-exploited-vulnerabilities-catalog
• FIRST EPSS (2026-11-03) api.first.org/data/v1/epss?cve=CVE-2026-109619