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CVE-2026-3591

CVE-2026-3591 · A stack use-after-return flaw in SIG(0) handling code may enable ACL bypass

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

A use-after-return vulnerability exists in the `named` server when handling DNS queries signed with SIG(0). Using a specially-crafted DNS request, an attacker may be able to cause an ACL to improperly (mis)match an IP address. In a default-allow ACL (denying only specific IP addresses), this may lead to unauthorized access. Default-deny ACLs should fail-secure. This issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1. BIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected.

CVSS 5.4 · Medium · EPSS 0.3% · Fix available

Published
Updated

Stack: system

Affected products and versions

  • bind 9

    Versions
    • ≥ 9.20.0, ≤ 9.20.20: Affected (custom)
    • ≥ 9.21.0, ≤ 9.21.19: Affected (custom)
    • ≥ 9.20.9-S1, ≤ 9.20.20-S1: Affected (custom)
    • ≥ 9.18.0, ≤ 9.18.46: Not affected (custom)
    • ≥ 9.18.11-S1, ≤ 9.18.46-S1: Not affected (custom)

    No fix published

  • bind9 Debian:13

    Versions
    • 1:9.20.11-4
    • 1:9.20.15-1
    • 1:9.20.15-1~deb13u1
    • 1:9.20.15-1~deb13u1~bpo12+1
    • 1:9.20.15-2
    • 1:9.20.18-1
    • 1:9.20.18-1~deb13u1
    • 1:9.20.18-1~deb13u1~bpo12+1
    • 1:9.20.19-1
    • 1:9.20.19-1~bpo12+1
    • 1:9.20.20-1
    • 1:9.20.20-1~bpo12+1
    • 1:9.20.21-1~deb13u1~bpo12+1
    Affected ranges
    • ECOSYSTEM: < 1:9.20.21-1~deb13u1

    Update to 1:9.20.21-1~deb13u1

  • bind9 Debian:14

    Versions
    • 1:9.20.11-4
    • 1:9.20.15-1
    • 1:9.20.15-1~deb13u1
    • 1:9.20.15-1~deb13u1~bpo12+1
    • 1:9.20.15-2
    • 1:9.20.18-1
    • 1:9.20.18-1~deb13u1
    • 1:9.20.18-1~deb13u1~bpo12+1
    • 1:9.20.19-1
    • 1:9.20.19-1~bpo12+1
    • 1:9.20.20-1
    • 1:9.20.20-1~bpo12+1
    • 1:9.20.21-1~deb13u1
    • 1:9.20.21-1~deb13u1~bpo12+1
    Affected ranges
    • ECOSYSTEM: < 1:9.20.21-1

    Update to 1:9.20.21-1

  • isc-dhcp Ubuntu:18.04:LTS

    Versions
    • 4.3.5-3ubuntu2
    • 4.3.5-3ubuntu3
    • 4.3.5-3ubuntu4
    • 4.3.5-3ubuntu5
    • 4.3.5-3ubuntu6
    • 4.3.5-3ubuntu7
    • 4.3.5-3ubuntu7.1
    • 4.3.5-3ubuntu7.2
    • 4.3.5-3ubuntu7.3
    • 4.3.5-3ubuntu7.4
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • bind9-libs Ubuntu:20.04:LTS

    Versions
    • 1:9.11.16+dfsg-3~build1
    • 1:9.11.16+dfsg-3~ubuntu1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • bind9-libs Ubuntu:22.04:LTS

    Versions
    • 1:9.11.19+dfsg-2.1ubuntu1
    • 1:9.11.19+dfsg-2.1ubuntu2
    • 1:9.11.19+dfsg-2.1ubuntu3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • isc-dhcp Ubuntu:24.04:LTS

    Versions
    • 4.4.3-P1-2ubuntu5
    • 4.4.3-P1-4ubuntu1
    • 4.4.3-P1-4ubuntu2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • bind9 Ubuntu:25.10

    Versions
    • 1:9.20.4-3ubuntu1
    • 1:9.20.4-3ubuntu2
    • 1:9.20.4-3ubuntu3
    • 1:9.20.9-2ubuntu1
    • 1:9.20.10-1ubuntu1
    • 1:9.20.11-1ubuntu1
    • 1:9.20.11-1ubuntu2
    • 1:9.20.11-1ubuntu2.1
    Affected ranges
    • ECOSYSTEM: < 1:9.20.11-1ubuntu2.2

    Update to 1:9.20.11-1ubuntu2.2

  • isc-dhcp Ubuntu:25.10

    Versions
    • 4.4.3-P1-4ubuntu2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • isc-dhcp Ubuntu:26.04:LTS

    Versions
    • 4.4.3-P1-4ubuntu2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

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