CVE catalog

CVE-2021-40083

knot-resolver: CVE-2021-40083

Severity: Medium
Published: Aug 25, 2021, 1:15:00 AM UTC
Source: [NVD] · [CVE record]
EPSS: 1.42% · Oct 25, 2026

Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case (NSEC3 with too many iterations used for a positive wildcard proof).

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	knot-resolver	sid	`6.5.0-2`	fixed
Debian	knot-resolver	forky	`6.4.2-1`	fixed
Debian	knot-resolver	trixie	`5.7.5-1`	fixed
Debian	knot-resolver	bookworm	`5.6.0-1+deb12u1`	fixed
Debian	knot-resolver	bookworm-security	`5.6.0-1+deb12u1`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	knot-resolver	source	sid	`5.4.1-2`	not yet assigned	Not reported	[991463]
Debian	knot-resolver	source	forky	`5.4.1-2`	not yet assigned	Not reported	[991463]
Debian	knot-resolver	source	trixie	`5.4.1-2`	not yet assigned	Not reported	[991463]
Debian	knot-resolver	source	bookworm	`5.4.1-2`	not yet assigned	Not reported	[991463]

[Debian bug #991463]

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[knot-resolver]Fixed
Details (4)
- 5.6.0-1+deb12u1 · amd64 · bookworm
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · bookworm; dsa · knot-resolver · debian · 12
- 5.6.0-1+deb12u1 · arm64 · bookworm
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · bookworm; dsa · knot-resolver · debian · 12
- 5.6.0-1+deb12u1 · amd64 · bookworm-security
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · bookworm; dsa · knot-resolver · debian · 12
- 5.6.0-1+deb12u1 · arm64 · bookworm-security
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · bookworm; dsa · knot-resolver · debian · 12
[knot-resolver-doc]Fixed
Source package: [knot-resolver]
Details (4)
- 5.6.0-1+deb12u1 · all · bookworm
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · bookworm; dsa · knot-resolver · debian · 12
- 5.6.0-1+deb12u1 · all · bookworm
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · bookworm; dsa · knot-resolver · debian · 12
- 5.6.0-1+deb12u1 · all · bookworm-security
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · bookworm; dsa · knot-resolver · debian · 12
- 5.6.0-1+deb12u1 · all · bookworm-security
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · bookworm; dsa · knot-resolver · debian · 12
[knot-resolver-module-http]Fixed
Source package: [knot-resolver]
Details (4)
- 5.6.0-1+deb12u1 · amd64 · bookworm
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · bookworm; dsa · knot-resolver · debian · 12
- 5.6.0-1+deb12u1 · arm64 · bookworm
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · bookworm; dsa · knot-resolver · debian · 12
- 5.6.0-1+deb12u1 · amd64 · bookworm-security
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · bookworm; dsa · knot-resolver · debian · 12
- 5.6.0-1+deb12u1 · arm64 · bookworm-security
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · bookworm; dsa · knot-resolver · debian · 12

[Debian 13 (Trixie)]

[knot-resolver]Fixed
Details (2)
- 5.7.5-1 · amd64 · trixie
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · 13
- 5.7.5-1 · arm64 · trixie
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · 13
[knot-resolver-doc]Fixed
Source package: [knot-resolver]
Details (2)
- 5.7.5-1 · all · trixie
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · 13
- 5.7.5-1 · all · trixie
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · 13
[knot-resolver-module-http]Fixed
Source package: [knot-resolver]
Details (2)
- 5.7.5-1 · amd64 · trixie
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · 13
- 5.7.5-1 · arm64 · trixie
  Fixed · Fixed: 5.4.1-2
  dsa · knot-resolver · debian · 13

Observed: Oct 23, 2026, 6:02:20 PM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [OSV Package Vulnerability Database]