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CVE-2026-11721

CVE-2026-11721 · Cache poisoning possible with label count discrepancy, RRSIG, and wildcards

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

It is possible for an attacker's zone to respond to a query with an RRSIG that has a smaller number of labels than the zone in which the RRSIG is contained. This causes `named` to produce a wildcard name for a zone that is shorter than the attacker's zone, which can result in cache poisoning. For this attack to have any effect, the resolver under attack must have set `synth-from-dnssec yes;` (which is the default). This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

CVSS 7.5 · High · EPSS 0.4% · Fix available

Published
Updated

Stack: system

Affected products and versions

  • bind 9

    Versions
    • ≥ 9.11.0, ≤ 9.18.50: Affected (custom)
    • ≥ 9.20.0, ≤ 9.20.24: Affected (custom)
    • ≥ 9.21.0, ≤ 9.21.23: Affected (custom)
    • ≥ 9.11.3-S1, ≤ 9.18.50-S1: Affected (custom)
    • ≥ 9.20.9-S1, ≤ 9.20.24-S1: Affected (custom)

    No fix published

  • bind9 Debian:12

    Versions
    • 1:9.18.12-1
    • 1:9.18.13-1
    • 1:9.18.16-1
    • 1:9.18.16-1~deb12u1
    • 1:9.18.16-1~deb12u1~bpo11+1
    • 1:9.18.19-1~deb12u1
    • 1:9.18.19-1~deb12u1~bpo11+1
    • 1:9.18.24-1
    • 1:9.18.24-1~bpo11+1
    • 1:9.18.28-1~deb12u1
    • 1:9.18.28-1~deb12u2
    • 1:9.18.33-1~deb12u2
    • 1:9.18.41-1~deb12u1
    • 1:9.18.44-1~deb12u1
    • 1:9.18.47-1~deb12u1
    • 1:9.18.49-1~deb12u1
    Affected ranges
    • ECOSYSTEM: < 1:9.18.49-1~deb12u2

    Update to 1:9.18.49-1~deb12u2

  • 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
    • 1:9.20.21-1~deb13u1
    • 1:9.20.21-1~deb13u1~bpo12+1
    • 1:9.20.22-1
    • 1:9.20.23-1
    • 1:9.20.23-1~deb13u1
    • 1:9.20.23-1~deb13u1~bpo12+1
    • 1:9.20.24-1
    • 1:9.20.26-1~deb13u1~bpo12+1
    Affected ranges
    • ECOSYSTEM: < 1:9.20.26-1~deb13u1

    Update to 1:9.20.26-1~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
    • 1:9.20.21-1~deb13u1
    • 1:9.20.21-1~deb13u1~bpo12+1
    • 1:9.20.22-1
    • 1:9.20.23-1
    • 1:9.20.23-1~deb13u1
    • 1:9.20.23-1~deb13u1~bpo12+1
    • 1:9.20.24-1
    • 1:9.20.26-1~deb13u1
    • 1:9.20.26-1~deb13u1~bpo12+1
    Affected ranges
    • ECOSYSTEM: < 1:9.20.26-1

    Update to 1:9.20.26-1

  • bind9 Ubuntu:Pro:14.04:LTS

    Versions
    • 1:9.9.3.dfsg.P2-4ubuntu1
    • 1:9.9.3.dfsg.P2-4ubuntu2
    • 1:9.9.3.dfsg.P2-4ubuntu3
    • 1:9.9.5.dfsg-2
    • 1:9.9.5.dfsg-3
    • 1:9.9.5.dfsg-3ubuntu0.1
    • 1:9.9.5.dfsg-3ubuntu0.2
    • 1:9.9.5.dfsg-3ubuntu0.3
    • 1:9.9.5.dfsg-3ubuntu0.4
    • 1:9.9.5.dfsg-3ubuntu0.5
    • 1:9.9.5.dfsg-3ubuntu0.6
    • 1:9.9.5.dfsg-3ubuntu0.7
    • 1:9.9.5.dfsg-3ubuntu0.8
    • 1:9.9.5.dfsg-3ubuntu0.9
    • 1:9.9.5.dfsg-3ubuntu0.10
    • 1:9.9.5.dfsg-3ubuntu0.11
    • 1:9.9.5.dfsg-3ubuntu0.12
    • 1:9.9.5.dfsg-3ubuntu0.13
    • 1:9.9.5.dfsg-3ubuntu0.14
    • 1:9.9.5.dfsg-3ubuntu0.15
    • 1:9.9.5.dfsg-3ubuntu0.16
    • 1:9.9.5.dfsg-3ubuntu0.17
    • 1:9.9.5.dfsg-3ubuntu0.18
    • 1:9.9.5.dfsg-3ubuntu0.19
    • 1:9.9.5.dfsg-3ubuntu0.19+esm1
    • 1:9.9.5.dfsg-3ubuntu0.19+esm2
    • 1:9.9.5.dfsg-3ubuntu0.19+esm3
    • 1:9.9.5.dfsg-3ubuntu0.19+esm4
    • 1:9.9.5.dfsg-3ubuntu0.19+esm5
    • 1:9.9.5.dfsg-3ubuntu0.19+esm6
    • 1:9.9.5.dfsg-3ubuntu0.19+esm7
    • 1:9.9.5.dfsg-3ubuntu0.19+esm9
    • 1:9.9.5.dfsg-3ubuntu0.19+esm10
    • 1:9.9.5.dfsg-3ubuntu0.19+esm11
    • 1:9.9.5.dfsg-3ubuntu0.19+esm12
    • 1:9.9.5.dfsg-3ubuntu0.19+esm13
    • 1:9.9.5.dfsg-3ubuntu0.19+esm14
    Affected ranges
    • ECOSYSTEM: < 1:9.9.5.dfsg-3ubuntu0.19+esm15

    Update to 1:9.9.5.dfsg-3ubuntu0.19+esm15

  • bind9 Ubuntu:Pro:16.04:LTS

    Versions
    • 1:9.9.5.dfsg-11ubuntu1
    • 1:9.9.5.dfsg-12
    • 1:9.9.5.dfsg-12.1
    • 1:9.9.5.dfsg-12.1ubuntu1
    • 1:9.10.3.dfsg.P2-4
    • 1:9.10.3.dfsg.P2-5
    • 1:9.10.3.dfsg.P4-3
    • 1:9.10.3.dfsg.P4-4
    • 1:9.10.3.dfsg.P4-5
    • 1:9.10.3.dfsg.P4-8
    • 1:9.10.3.dfsg.P4-8ubuntu1
    • 1:9.10.3.dfsg.P4-8ubuntu1.1
    • 1:9.10.3.dfsg.P4-8ubuntu1.2
    • 1:9.10.3.dfsg.P4-8ubuntu1.3
    • 1:9.10.3.dfsg.P4-8ubuntu1.4
    • 1:9.10.3.dfsg.P4-8ubuntu1.5
    • 1:9.10.3.dfsg.P4-8ubuntu1.6
    • 1:9.10.3.dfsg.P4-8ubuntu1.7
    • 1:9.10.3.dfsg.P4-8ubuntu1.8
    • 1:9.10.3.dfsg.P4-8ubuntu1.9
    • 1:9.10.3.dfsg.P4-8ubuntu1.10
    • 1:9.10.3.dfsg.P4-8ubuntu1.11
    • 1:9.10.3.dfsg.P4-8ubuntu1.12
    • 1:9.10.3.dfsg.P4-8ubuntu1.14
    • 1:9.10.3.dfsg.P4-8ubuntu1.15
    • 1:9.10.3.dfsg.P4-8ubuntu1.16
    • 1:9.10.3.dfsg.P4-8ubuntu1.17
    • 1:9.10.3.dfsg.P4-8ubuntu1.18
    • 1:9.10.3.dfsg.P4-8ubuntu1.19
    • 1:9.10.3.dfsg.P4-8ubuntu1.19+esm1
    • 1:9.10.3.dfsg.P4-8ubuntu1.19+esm2
    • 1:9.10.3.dfsg.P4-8ubuntu1.19+esm3
    • 1:9.10.3.dfsg.P4-8ubuntu1.19+esm5
    • 1:9.10.3.dfsg.P4-8ubuntu1.19+esm6
    • 1:9.10.3.dfsg.P4-8ubuntu1.19+esm7
    • 1:9.10.3.dfsg.P4-8ubuntu1.19+esm8
    • 1:9.10.3.dfsg.P4-8ubuntu1.19+esm9
    • 1:9.10.3.dfsg.P4-8ubuntu1.19+esm10
    Affected ranges
    • ECOSYSTEM: < 1:9.10.3.dfsg.P4-8ubuntu1.19+esm11

    Update to 1:9.10.3.dfsg.P4-8ubuntu1.19+esm11

  • bind9 Ubuntu:Pro:18.04:LTS

    Versions
    • 1:9.10.3.dfsg.P4-12.6ubuntu1
    • 1:9.11.2.P1-1ubuntu2
    • 1:9.11.2.P1-1ubuntu3
    • 1:9.11.2.P1-1ubuntu4
    • 1:9.11.2.P1-1ubuntu5
    • 1:9.11.3+dfsg-1ubuntu1
    • 1:9.11.3+dfsg-1ubuntu1.1
    • 1:9.11.3+dfsg-1ubuntu1.2
    • 1:9.11.3+dfsg-1ubuntu1.3
    • 1:9.11.3+dfsg-1ubuntu1.5
    • 1:9.11.3+dfsg-1ubuntu1.7
    • 1:9.11.3+dfsg-1ubuntu1.8
    • 1:9.11.3+dfsg-1ubuntu1.9
    • 1:9.11.3+dfsg-1ubuntu1.10
    • 1:9.11.3+dfsg-1ubuntu1.11
    • 1:9.11.3+dfsg-1ubuntu1.12
    • 1:9.11.3+dfsg-1ubuntu1.13
    • 1:9.11.3+dfsg-1ubuntu1.14
    • 1:9.11.3+dfsg-1ubuntu1.15
    • 1:9.11.3+dfsg-1ubuntu1.16
    • 1:9.11.3+dfsg-1ubuntu1.17
    • 1:9.11.3+dfsg-1ubuntu1.18
    • 1:9.11.3+dfsg-1ubuntu1.19+esm1
    • 1:9.11.3+dfsg-1ubuntu1.19+esm2
    • 1:9.11.3+dfsg-1ubuntu1.19+esm3
    • 1:9.11.3+dfsg-1ubuntu1.19+esm4
    • 1:9.11.3+dfsg-1ubuntu1.19+esm5
    Affected ranges
    • ECOSYSTEM: < 1:9.11.3+dfsg-1ubuntu1.19+esm6

    Update to 1:9.11.3+dfsg-1ubuntu1.19+esm6

  • 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 Ubuntu:Pro:20.04:LTS

    Versions
    • 1:9.11.5.P4+dfsg-5.1ubuntu2
    • 1:9.11.5.P4+dfsg-5.1ubuntu3
    • 1:9.11.5.P4+dfsg-5.1ubuntu4
    • 1:9.11.5.P4+dfsg-5.1ubuntu5
    • 1:9.11.14+dfsg-1ubuntu1
    • 1:9.11.14+dfsg-3ubuntu1
    • 1:9.16.0-1ubuntu3
    • 1:9.16.0-1ubuntu4
    • 1:9.16.0-1ubuntu5
    • 1:9.16.1-0ubuntu1
    • 1:9.16.1-0ubuntu2
    • 1:9.16.1-0ubuntu2.1
    • 1:9.16.1-0ubuntu2.2
    • 1:9.16.1-0ubuntu2.3
    • 1:9.16.1-0ubuntu2.4
    • 1:9.16.1-0ubuntu2.6
    • 1:9.16.1-0ubuntu2.7
    • 1:9.16.1-0ubuntu2.8
    • 1:9.16.1-0ubuntu2.9
    • 1:9.16.1-0ubuntu2.10
    • 1:9.16.1-0ubuntu2.11
    • 1:9.16.1-0ubuntu2.12
    • 1:9.16.1-0ubuntu2.14
    • 1:9.16.1-0ubuntu2.15
    • 1:9.16.1-0ubuntu2.16
    • 1:9.16.48-0ubuntu0.20.04.1
    • 1:9.18.28-0ubuntu0.20.04.1
    • 1:9.18.30-0ubuntu0.20.04.1
    • 1:9.18.30-0ubuntu0.20.04.2
    • 1:9.18.30-0ubuntu0.20.04.2+esm1
    • 1:9.18.30-0ubuntu0.20.04.2+esm2
    Affected ranges
    • ECOSYSTEM: < 1:9.18.30-0ubuntu0.20.04.2+esm3

    Update to 1:9.18.30-0ubuntu0.20.04.2+esm3

  • 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 Ubuntu:22.04:LTS

    Versions
    • 1:9.16.15-1ubuntu1
    • 1:9.16.15-1ubuntu2
    • 1:9.16.15-1ubuntu3
    • 1:9.18.0-2ubuntu1
    • 1:9.18.0-2ubuntu2
    • 1:9.18.0-2ubuntu3
    • 1:9.18.1-1ubuntu1
    • 1:9.18.1-1ubuntu1.1
    • 1:9.18.1-1ubuntu1.2
    • 1:9.18.1-1ubuntu1.3
    • 1:9.18.12-0ubuntu0.22.04.1
    • 1:9.18.12-0ubuntu0.22.04.2
    • 1:9.18.12-0ubuntu0.22.04.3
    • 1:9.18.18-0ubuntu0.22.04.1
    • 1:9.18.18-0ubuntu0.22.04.2
    • 1:9.18.24-0ubuntu0.22.04.1
    • 1:9.18.28-0ubuntu0.22.04.1
    • 1:9.18.30-0ubuntu0.22.04.1
    • 1:9.18.30-0ubuntu0.22.04.2
    • 1:9.18.39-0ubuntu0.22.04.1
    • 1:9.18.39-0ubuntu0.22.04.2
    • 1:9.18.39-0ubuntu0.22.04.3
    • 1:9.18.39-0ubuntu0.22.04.4
    Affected ranges
    • ECOSYSTEM: < 1:9.18.39-0ubuntu0.22.04.5

    Update to 1:9.18.39-0ubuntu0.22.04.5

  • 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

  • bind9 Ubuntu:24.04:LTS

    Versions
    • 1:9.18.18-0ubuntu2
    • 1:9.18.21-0ubuntu1
    • 1:9.18.24-0ubuntu3
    • 1:9.18.24-0ubuntu4
    • 1:9.18.24-0ubuntu5
    • 1:9.18.28-0ubuntu0.24.04.1
    • 1:9.18.30-0ubuntu0.24.04.1
    • 1:9.18.30-0ubuntu0.24.04.2
    • 1:9.18.39-0ubuntu0.24.04.1
    • 1:9.18.39-0ubuntu0.24.04.2
    • 1:9.18.39-0ubuntu0.24.04.3
    • 1:9.18.39-0ubuntu0.24.04.5
    Affected ranges
    • ECOSYSTEM: < 1:9.18.39-0ubuntu0.24.04.6

    Update to 1:9.18.39-0ubuntu0.24.04.6

  • 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:26.04:LTS

    Versions
    • 1:9.20.11-1ubuntu2
    • 1:9.20.11-1ubuntu3
    • 1:9.20.18-1ubuntu1
    • 1:9.20.18-1ubuntu2
    • 1:9.20.18-1ubuntu2.1
    • 1:9.20.24-1ubuntu0.1
    Affected ranges
    • ECOSYSTEM: < 1:9.20.24-1ubuntu0.2

    Update to 1:9.20.24-1ubuntu0.2

  • isc-dhcp Ubuntu:26.04:LTS

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

    No fix published

Original sources

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