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TI-2026-61979 Aliases CVE-2026-91768

IPv6 ACL bypass in FastCGI listen.allowed_clients due to partial address comparison (memcmp 12 bytes)

Priority LOW 29CWE-1023Published · Updated

Key facts

Attack vector
Adjacent network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · None · None
Fix status
Partial Red Hat: 2 fixed, 5 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.

Summary

The IPv6 branch of the FastCGI client access check compares only the first 12 bytes of a 16-byte IPv6 address, so listen.allowed_clients matches on a /96 prefix instead of the exact address. An attacker who can source an address sharing the first 96 bits with an allowed one passes the check and reaches the FastCGI endpoint.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00376 31st percentileScored 2026-11-07
Fix Partial PHP (PHP Group): 8.2.34, 8.3.35, 8.4.26 +1Red Hat: 2 advisoriesRed Hat: 2 fixed, 5 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
PHP GroupPHPbefore 8.2.34; before 8.3.35; before 8.4.26; before 8.5.118.2.34, 8.3.35, 8.4.26, 8.5.11Patch availableCNA
  • PHP VendorPHP Group Affected before 8.2.34; before 8.3.35; before 8.4.26; before 8.5.11 Fixed in 8.2.34, 8.3.35, 8.4.26, 8.5.11 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:php:php:*:*:*:*:*:*:*:*8.2.0 to before 8.2.34; 8.3.0 to before 8.3.35; 8.4.0 to before 8.4.26; 8.5.0 to before 8.5.11VulnerablePHP
  • cpe:2.3:a:php:php:*:*:*:*:*:*:*:* Versions 8.2.0 to before 8.2.34; 8.3.0 to before 8.3.35; 8.4.0 to before 8.4.26; 8.5.0 to before 8.5.11 Vulnerable ·PHP

Remediation

  • Fix · CNA PHP (PHP Group) Fixed in 8.2.34, 8.3.35, 8.4.26, 8.5.11

Red Hat 2 advisories

  • RHSA-2026:87080 Released 2026-10-21 · Red Hat rating Important
    php:7.4 security update
    • Red Hat Enterprise Linux AppStream (v. 8) apcu-panel-5.1.18-1.module+el8.10.0+22485+a3539972.noarch::php:7.4, libzip-1.6.1-1.module+el8.10.0+22485+a3539972.aarch64::php:7.4, libzip-1.6.1-1.module+el8.10.0+22485+a3539972.ppc64le::php:7.4 +47
  • RHSA-2026:70720 Released 2026-09-23 · Red Hat rating Important
    Red Hat Hardened Images RPMs bug fix and enhancement update
    • Red Hat Hardened Images php-8.5.11-2.hum1@aarch64, php-8.5.11-2.hum1@src, php-8.5.11-2.hum1@x86_64 +47

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    PHP 8.2.34, 8.3.35 and 2 more versions

    11 records Highest priority Priority HIGH 1 HIGH, 3 MEDIUM, 7 LOW

    Other records, highest priority first

    • TI-2026-63096 Out-of-bounds read in the HTTP stream wrapper when following a redirect with an empty Location headerPriority HIGH 65
    • TI-2026-14392 PHP on Windows: Reserved Device Names Are Not Rejected Before File/Stream I/O which can cause DoSPriority MEDIUM 64
    • TI-2025-12959 Integer overflow to buffer overflow in soap HTTP parsingPriority MEDIUM 62
    Show all 11 records →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 10AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 8AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 9AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2026:87080
Red Hat Hardened ImagesFixed RHSA-2026:70720

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-91768
  2. 2026-10-21 Fix available: RHSA-2026:87080 · Red Hat
  3. 2026-10-21 Fix available: Red Hat Enterprise Linux AppStream (v. 8) · Red Hat

References

Advisory 1

  • TI-2024-04260 Argument Injection in PHP-CGI KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-78794 PHP remote code execution via stale global state KEVCVSS 4.0CRITICAL 9.2
  • TI-2026-78793 Out-of-memory handling flaw in PHP allows remote code execution KEVCVSS 4.0CRITICAL 9.2
  • TI-2024-01743 Command injection via array-ish $command parameter of proc_open() CVSS 3.1CRITICAL 9.4
  • TI-2022-13555 PDO::quote() may return unquoted string CVSS 3.1CRITICAL 9.1
  • TI-2024-10408 Reference counting in php_request_shutdown causes Use-After-Free CVSS 4.0CRITICAL 9.2
See all 107 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences