p PatchFirst

CVE-2026-91768

CVE-2026-91768 · IPv6 ACL bypass in FastCGI listen.allowed_clients due to partial address comparison (memcmp 12 bytes)

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 6.5 · Medium · EPSS 0.6% · Fix available

Published
Updated

Stack: system · php

Affected products and versions

  • php

    Versions
    • ≥ 8.2.*, < 8.2.34: Affected (semver)
    • ≥ 8.3.*, < 8.3.35: Affected (semver)
    • ≥ 8.4.*, < 8.4.26: Affected (semver)
    • ≥ 8.5.*, < 8.5.11: Affected (semver)

    Update to 8.2.34; Update to 8.3.35; Update to 8.4.26; Update to 8.5.11

  • php8.2 Debian:12

    Versions
    • 8.2.10-1
    • 8.2.10-2
    • 8.2.12-1
    • 8.2.16-1
    • 8.2.16-2
    • 8.2.17-1
    • 8.2.18-1
    • 8.2.18-1~deb12u1
    • 8.2.20-1~deb12u1
    • 8.2.20-2
    • 8.2.20-3
    • 8.2.21-1
    • 8.2.23-1
    • 8.2.24-1
    • 8.2.24-1~deb12u1
    • 8.2.26-1~deb12u1
    • 8.2.26-4
    • 8.2.27-1
    • 8.2.28-1~deb12u1
    • 8.2.29-1~deb12u1
    • 8.2.30-1~deb12u1
    • 8.2.31-1~deb12u1
    • 8.2.32-1~deb12u1
    • 8.2.33-1~deb12u1
    • 8.2.5-2
    • 8.2.7-1
    • 8.2.7-1.1
    • 8.2.7-1.2
    • 8.2.7-1~deb12u1
    Affected ranges
    • ECOSYSTEM: < 8.2.34-1~deb12u1

    Update to 8.2.34-1~deb12u1

  • php8.4 Debian:13

    Versions
    • 8.4.11-1
    • 8.4.16-1
    • 8.4.16-1~deb13u1
    • 8.4.20-1
    • 8.4.21-1
    • 8.4.21-1~deb13u1
    • 8.4.22-1
    • 8.4.23-1
    • 8.4.23-1~deb13u1
    • 8.4.24-1
    • 8.4.24-1~deb13u1
    Affected ranges
    • ECOSYSTEM: < 8.4.26-1~deb13u1

    Update to 8.4.26-1~deb13u1

  • php8.4 Debian:14

    Versions
    • 8.4.11-1
    • 8.4.16-1
    • 8.4.16-1~deb13u1
    • 8.4.20-1
    • 8.4.21-1
    • 8.4.21-1~deb13u1
    • 8.4.22-1
    • 8.4.23-1
    • 8.4.23-1~deb13u1
    • 8.4.24-1
    • 8.4.24-1~deb13u1
    • 8.4.26-1~deb13u1
    Affected ranges
    • ECOSYSTEM: < 8.4.26-1

    Update to 8.4.26-1

  • php7.0 Ubuntu:Pro:16.04:LTS

    Versions
    • 7.0.1-5
    • 7.0.1-6
    • 7.0.2-1
    • 7.0.2-3
    • 7.0.2-4
    • 7.0.2-5
    • 7.0.3-2
    • 7.0.3-3
    • 7.0.3-9ubuntu1
    • 7.0.4-5ubuntu1
    • 7.0.4-5ubuntu2
    • 7.0.4-7ubuntu1
    • 7.0.4-7ubuntu2
    • 7.0.4-7ubuntu2.1
    • 7.0.8-0ubuntu0.16.04.1
    • 7.0.8-0ubuntu0.16.04.2
    • 7.0.8-0ubuntu0.16.04.3
    • 7.0.13-0ubuntu0.16.04.1
    • 7.0.15-0ubuntu0.16.04.1
    • 7.0.15-0ubuntu0.16.04.2
    • 7.0.15-0ubuntu0.16.04.4
    • 7.0.18-0ubuntu0.16.04.1
    • 7.0.22-0ubuntu0.16.04.1
    • 7.0.25-0ubuntu0.16.04.1
    • 7.0.28-0ubuntu0.16.04.1
    • 7.0.30-0ubuntu0.16.04.1
    • 7.0.32-0ubuntu0.16.04.1
    • 7.0.33-0ubuntu0.16.04.1
    • 7.0.33-0ubuntu0.16.04.2
    • 7.0.33-0ubuntu0.16.04.3
    • 7.0.33-0ubuntu0.16.04.4
    • 7.0.33-0ubuntu0.16.04.5
    • 7.0.33-0ubuntu0.16.04.6
    • 7.0.33-0ubuntu0.16.04.7
    • 7.0.33-0ubuntu0.16.04.9
    • 7.0.33-0ubuntu0.16.04.11
    • 7.0.33-0ubuntu0.16.04.12
    • 7.0.33-0ubuntu0.16.04.14
    • 7.0.33-0ubuntu0.16.04.15
    • 7.0.33-0ubuntu0.16.04.16
    • 7.0.33-0ubuntu0.16.04.16+esm1
    • 7.0.33-0ubuntu0.16.04.16+esm2
    • 7.0.33-0ubuntu0.16.04.16+esm3
    • 7.0.33-0ubuntu0.16.04.16+esm4
    • 7.0.33-0ubuntu0.16.04.16+esm5
    • 7.0.33-0ubuntu0.16.04.16+esm6
    • 7.0.33-0ubuntu0.16.04.16+esm7
    • 7.0.33-0ubuntu0.16.04.16+esm8
    • 7.0.33-0ubuntu0.16.04.16+esm9
    • 7.0.33-0ubuntu0.16.04.16+esm10
    • 7.0.33-0ubuntu0.16.04.16+esm11
    • 7.0.33-0ubuntu0.16.04.16+esm12
    • 7.0.33-0ubuntu0.16.04.16+esm13
    • 7.0.33-0ubuntu0.16.04.16+esm14
    • 7.0.33-0ubuntu0.16.04.16+esm15
    • 7.0.33-0ubuntu0.16.04.16+esm16
    • 7.0.33-0ubuntu0.16.04.16+esm17
    • 7.0.33-0ubuntu0.16.04.16+esm18
    • 7.0.33-0ubuntu0.16.04.16+esm19
    • 7.0.33-0ubuntu0.16.04.16+esm20
    Affected ranges
    • ECOSYSTEM: < 7.0.33-0ubuntu0.16.04.16+esm21

    Update to 7.0.33-0ubuntu0.16.04.16+esm21

  • php7.2 Ubuntu:Pro:18.04:LTS

    Versions
    • 7.2.1-1ubuntu2
    • 7.2.2-1ubuntu1
    • 7.2.2-1ubuntu2
    • 7.2.3-1ubuntu1
    • 7.2.5-0ubuntu0.18.04.1
    • 7.2.7-0ubuntu0.18.04.1
    • 7.2.7-0ubuntu0.18.04.2
    • 7.2.10-0ubuntu0.18.04.1
    • 7.2.15-0ubuntu0.18.04.1
    • 7.2.15-0ubuntu0.18.04.2
    • 7.2.17-0ubuntu0.18.04.1
    • 7.2.19-0ubuntu0.18.04.1
    • 7.2.19-0ubuntu0.18.04.2
    • 7.2.24-0ubuntu0.18.04.1
    • 7.2.24-0ubuntu0.18.04.2
    • 7.2.24-0ubuntu0.18.04.3
    • 7.2.24-0ubuntu0.18.04.4
    • 7.2.24-0ubuntu0.18.04.6
    • 7.2.24-0ubuntu0.18.04.7
    • 7.2.24-0ubuntu0.18.04.8
    • 7.2.24-0ubuntu0.18.04.9
    • 7.2.24-0ubuntu0.18.04.10
    • 7.2.24-0ubuntu0.18.04.11
    • 7.2.24-0ubuntu0.18.04.12
    • 7.2.24-0ubuntu0.18.04.13
    • 7.2.24-0ubuntu0.18.04.15
    • 7.2.24-0ubuntu0.18.04.16
    • 7.2.24-0ubuntu0.18.04.17
    • 7.2.24-0ubuntu0.18.04.17+esm1
    • 7.2.24-0ubuntu0.18.04.17+esm2
    • 7.2.24-0ubuntu0.18.04.17+esm3
    • 7.2.24-0ubuntu0.18.04.17+esm4
    • 7.2.24-0ubuntu0.18.04.17+esm5
    • 7.2.24-0ubuntu0.18.04.17+esm6
    • 7.2.24-0ubuntu0.18.04.17+esm7
    • 7.2.24-0ubuntu0.18.04.17+esm8
    • 7.2.24-0ubuntu0.18.04.17+esm9
    • 7.2.24-0ubuntu0.18.04.17+esm10
    • 7.2.24-0ubuntu0.18.04.17+esm11
    • 7.2.24-0ubuntu0.18.04.17+esm12
    Affected ranges
    • ECOSYSTEM: < 7.2.24-0ubuntu0.18.04.17+esm13

    Update to 7.2.24-0ubuntu0.18.04.17+esm13

  • php7.4 Ubuntu:Pro:20.04:LTS

    Versions
    • 7.4.3-4build1
    • 7.4.3-4build2
    • 7.4.3-4ubuntu1
    • 7.4.3-4ubuntu1.1
    • 7.4.3-4ubuntu2.2
    • 7.4.3-4ubuntu2.4
    • 7.4.3-4ubuntu2.5
    • 7.4.3-4ubuntu2.6
    • 7.4.3-4ubuntu2.7
    • 7.4.3-4ubuntu2.8
    • 7.4.3-4ubuntu2.9
    • 7.4.3-4ubuntu2.10
    • 7.4.3-4ubuntu2.11
    • 7.4.3-4ubuntu2.12
    • 7.4.3-4ubuntu2.13
    • 7.4.3-4ubuntu2.15
    • 7.4.3-4ubuntu2.16
    • 7.4.3-4ubuntu2.17
    • 7.4.3-4ubuntu2.18
    • 7.4.3-4ubuntu2.19
    • 7.4.3-4ubuntu2.20
    • 7.4.3-4ubuntu2.22
    • 7.4.3-4ubuntu2.23
    • 7.4.3-4ubuntu2.24
    • 7.4.3-4ubuntu2.26
    • 7.4.3-4ubuntu2.28
    • 7.4.3-4ubuntu2.29
    • 7.4.3-4ubuntu2.29+esm1
    • 7.4.3-4ubuntu2.29+esm2
    • 7.4.3-4ubuntu2.29+esm3
    Affected ranges
    • ECOSYSTEM: < 7.4.3-4ubuntu2.29+esm4

    Update to 7.4.3-4ubuntu2.29+esm4

  • php8.1 Ubuntu:22.04:LTS

    Versions
    • 8.1.0~rc4-1ubuntu2
    • 8.1.0-1
    • 8.1.2-1ubuntu1
    • 8.1.2-1ubuntu2
    • 8.1.2-1ubuntu2.1
    • 8.1.2-1ubuntu2.2
    • 8.1.2-1ubuntu2.3
    • 8.1.2-1ubuntu2.4
    • 8.1.2-1ubuntu2.5
    • 8.1.2-1ubuntu2.6
    • 8.1.2-1ubuntu2.8
    • 8.1.2-1ubuntu2.9
    • 8.1.2-1ubuntu2.10
    • 8.1.2-1ubuntu2.11
    • 8.1.2-1ubuntu2.13
    • 8.1.2-1ubuntu2.14
    • 8.1.2-1ubuntu2.15
    • 8.1.2-1ubuntu2.17
    • 8.1.2-1ubuntu2.18
    • 8.1.2-1ubuntu2.19
    • 8.1.2-1ubuntu2.20
    • 8.1.2-1ubuntu2.21
    • 8.1.2-1ubuntu2.22
    • 8.1.2-1ubuntu2.23
    • 8.1.2-1ubuntu2.24
    • 8.1.2-1ubuntu2.25
    • 8.1.2-1ubuntu2.26
    Affected ranges
    • ECOSYSTEM: < 8.1.2-1ubuntu2.27

    Update to 8.1.2-1ubuntu2.27

  • php8.3 Ubuntu:24.04:LTS

    Versions
    • 8.3.0-1
    • 8.3.0-1ubuntu1
    • 8.3.4-1
    • 8.3.4-1build1
    • 8.3.6-0maysync1
    • 8.3.6-0ubuntu0.24.04.1
    • 8.3.6-0ubuntu0.24.04.2
    • 8.3.6-0ubuntu0.24.04.3
    • 8.3.6-0ubuntu0.24.04.4
    • 8.3.6-0ubuntu0.24.04.5
    • 8.3.6-0ubuntu0.24.04.6
    • 8.3.6-0ubuntu0.24.04.7
    • 8.3.6-0ubuntu0.24.04.8
    • 8.3.6-0ubuntu0.24.04.9
    • 8.3.6-0ubuntu0.24.04.10
    • 8.3.6-0ubuntu0.24.04.11
    Affected ranges
    • ECOSYSTEM: < 8.3.6-0ubuntu0.24.04.12

    Update to 8.3.6-0ubuntu0.24.04.12

  • php8.5 Ubuntu:26.10

    Versions
    • 8.5.4-0ubuntu1
    • 8.5.4-0ubuntu3
    • 8.5.9-0ubuntu1
    Affected ranges
    • ECOSYSTEM: < 8.5.9-0ubuntu2

    Update to 8.5.9-0ubuntu2

  • php8.5 Ubuntu:26.04:LTS

    Versions
    • 8.5.2-0ubuntu1
    • 8.5.4-0ubuntu1
    • 8.5.4-0ubuntu1.1
    • 8.5.4-0ubuntu1.2
    • 8.5.4-0ubuntu1.3
    Affected ranges
    • ECOSYSTEM: < 8.5.4-0ubuntu1.4

    Update to 8.5.4-0ubuntu1.4

Original sources

Check your server →