CVE-2026-5947 Affecting bind9 package, versions <1:9.20.11-1ubuntu2.4


Severity

Recommended
0.0
medium
0
10

Based on Ubuntu security rating.

Threat Intelligence

EPSS
1.39% (69th percentile)

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  • Snyk IDSNYK-UBUNTU2510-BIND9-16777093
  • published22 May 2026
  • disclosed20 May 2026

Introduced: 20 May 2026

CVE-2026-5947  (opens in a new tab)

How to fix?

Upgrade Ubuntu:25.10 bind9 to version 1:9.20.11-1ubuntu2.4 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream bind9 package and not the bind9 package as distributed by Ubuntu. See How to fix? for Ubuntu:25.10 relevant fixed versions and status.

Undefined behavior may result due to a race condition leading to a use-after-free violation. If BIND receives an incoming DNS message signed with SIG(0), it begins work to validate that signature. If, during that validation, the "recursive-clients" limit is reached (as would occur during a query flood), and that same DNS message is discarded per the limit, there is a brief window of time while the SIG(0) validation may attempt to read the now-discarded DNS message. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.28 through 9.18.49 and 9.18.28-S1 through 9.18.49-S1 are NOT affected.

CVSS Base Scores

version 3.1