Core PHP RCE affecting widely deployed web servers and hosting stacks; exploit can fully compromise servers and is highly newsworthy.
CVE-2026-109618
PHP OOM handling flaw enables remote code execution via uninitialized memory.
Can a WAF block it? Partly. AWS WAF and Cloudflare publish WAF rules written for this CVE. Such rules block the known exploit requests and buy time, but attackers can change the request to get past them, so they do not replace the patch.
AWS WAF · 2 rules · since 21 Oct 2026
- PHP2Shell_BODY · PHP application managed rule group
- PHP2Shell_BODY_Extended · PHP application managed rule group
Cloudflare · 14 rules (Block) · since 22 Oct 2026
- PHP Remote Code Execution Attack (CVE-2026-109618, CVE-2026-109619) #2 · Cloudflare Free Ruleset
- PHP Remote Code Execution Attack (CVE-2026-109618, CVE-2026-109619) #7 · Cloudflare Free Ruleset
- PHP Remote Code Execution Attack (CVE-2026-109618, CVE-2026-109619) #7 · Cloudflare Managed Ruleset
- PHP Remote Code Execution Attack (CVE-2026-109618, CVE-2026-109619) #6 · Cloudflare Free Ruleset
- PHP Remote Code Execution Attack (CVE-2026-109618, CVE-2026-109619) #4 · Cloudflare Managed Ruleset
- PHP Remote Code Execution Attack (CVE-2026-109618, CVE-2026-109619) #4 · Cloudflare Free Ruleset
- PHP Remote Code Execution Attack (CVE-2026-109618, CVE-2026-109619) #5 · Cloudflare Managed Ruleset
- PHP Remote Code Execution Attack (CVE-2026-109618, CVE-2026-109619) #6 · Cloudflare Managed Ruleset
- and 6 more
Also consider: patch · enable the vendor rule in block mode
Based on WAF vendor rules published for this CVE. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Is CVE-2026-109618 being exploited?
Yes. CVE-2026-109618 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2026-109618?
CVE-2026-109618 is rated Critical with a CVSS score of 9.2. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-109618?
Yes. A fix has been recorded for CVE-2026-109618. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-109618 affect?
CVE-2026-109618 affects PHP (php-src) core, PHP-FPM, mod_php, Web applications using PHP. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-109618?
Apply PHP security update immediately and restart PHP services; audit exposed hosts.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution on PHP servers via longjmp OOM handling leading to use-after-free/uninitialized memory; full host compromise possible.
Immediate action required
- affected>= 8.2.* and < 8.2.35
- affected>= 8.3.* and < 8.3.36
- affected>= 8.4.* and < 8.4.27
- affected>= 8.5.* and < 8.5.12
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.