Medium

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

Type: advisorySource: Official CVE List1 source record

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.

Announced 25 Sept 2026Group revision 1

Original source ↗

CVE-2026-91768

Primary source · Revision 4

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-91768

PHP

Source reference: /containers/cna/affected/0/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "vendor": "PHP Group",
    "product": "PHP",
    "versions": [
      {
        "status": "affected",
        "version": "8.2.*",
        "lessThan": "8.2.34",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "8.3.*",
        "lessThan": "8.3.35",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "8.4.*",
        "lessThan": "8.4.26",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "8.5.*",
        "lessThan": "8.5.11",
        "versionType": "semver"
      }
    ],
    "packageName": "PHP-FPM",
    "defaultStatus": "unaffected"
  }
]