CVE catalog

CVE-2026-35501

unbound: CVE-2026-35501

Severity: Low · CVSS 3.7CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Published: Oct 21, 2026, 9:17:07 AM UTC
Source: [NVD] · [CVE record]
EPSS: 0.11% · Oct 25, 2026

When NLnet Labs Unbound 1.0.1 up to and including version 1.26.1 is configured with both a root trust anchor and an additional 'trust-anchor:' for an island-of-security zone whose parent is provably insecure under the root chain, a malicious actor with a forged NSEC reply with the SOA bit cleared can trick Unbound to treat the configured trust island as insecure. This happens because the DNSSEC validator in Unbound accepts and caches the NSEC insecure response bypassing the RRSIG validation that the validator was supposed to do. The acceptance of the NSEC record at the trust anchor apex was allowed due to and old fix for type DS and NSEC queries from clients when trust anchor for that name existed.

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	unbound	sid	`1.26.2-1`	fixed
Debian	unbound	forky	`1.26.2-1`	fixed
Debian	unbound	trixie	`1.22.0-2+deb13u3`	vulnerable
Debian	unbound	trixie-security	`1.26.2-0+deb13u1`	fixed
Debian	unbound	bookworm	`1.17.1-2+deb12u4`	vulnerable
Debian	unbound	bookworm-security	`1.17.1-2+deb12u3`	vulnerable
Ubuntu	unbound	pro	`1.9.0-2ubuntu1`	vulnerable
Ubuntu	unbound	pro	`1.9.0-2ubuntu2`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1.1`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1.2`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1.3`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1.4`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1.5`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1.6`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1.8`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1.9`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1.11`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1.11+esm1`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1.11+esm2`	vulnerable
Ubuntu	unbound	pro	`1.9.4-2ubuntu1.11+esm3`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu1`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu3`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.1`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.2`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.3`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.4`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.5`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.7`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.8`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.10`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.11`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.12`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.13`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.14`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.15`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.16`	vulnerable
Ubuntu	unbound	22.04	`1.13.1-1ubuntu5.17`	vulnerable
Ubuntu	unbound	24.04	`1.17.1-2`	vulnerable
Ubuntu	unbound	24.04	`1.18.0-2ubuntu1`	vulnerable
Ubuntu	unbound	24.04	`1.18.0-2ubuntu2`	vulnerable
Ubuntu	unbound	24.04	`1.19.1-1ubuntu1`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu1`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu3`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu3.1`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu3.2`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu3.3`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu3.4`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu3.5`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu3.6`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu3.7`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu3.8`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu3.9`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu3.10`	vulnerable
Ubuntu	unbound	24.04	`1.19.2-1ubuntu3.12`	vulnerable
Ubuntu	unbound	26.10	`1.24.2-1ubuntu2`	vulnerable
Ubuntu	unbound	26.10	`1.25.1-1ubuntu1`	vulnerable
Ubuntu	unbound	26.10	`1.25.1-1ubuntu3`	vulnerable
Ubuntu	unbound	26.04	`1.22.0-2ubuntu2`	vulnerable
Ubuntu	unbound	26.04	`1.22.0-2ubuntu4`	vulnerable
Ubuntu	unbound	26.04	`1.24.2-1ubuntu1`	vulnerable
Ubuntu	unbound	26.04	`1.24.2-1ubuntu2`	vulnerable
Ubuntu	unbound	26.04	`1.24.2-1ubuntu2.1`	vulnerable
Ubuntu	unbound	26.04	`1.24.2-1ubuntu2.2`	vulnerable
Ubuntu	unbound	26.04	`1.24.2-1ubuntu2.3`	vulnerable
Ubuntu	unbound	26.04	`1.24.2-1ubuntu2.4`	vulnerable

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	unbound	source	sid	`1.26.2-1`	not yet assigned	Not reported	Not reported
Debian	unbound	source	forky	`1.26.2-1`	not yet assigned	Not reported	Not reported
Debian	unbound	source	trixie	`1.26.2-0+deb13u1`	not yet assigned	Not reported	Not reported
Debian	unbound	source	bookworm	`(unfixed)`	not yet assigned	Not reported	Not reported

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[libunbound8]Affected
Source package: [unbound]
Details (4)
- 1.17.1-2+deb12u4 · amd64 · bookworm
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u4 · arm64 · bookworm
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u3 · amd64 · bookworm-security
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u3 · arm64 · bookworm-security
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
[libunbound-dev]Affected
Source package: [unbound]
Details (4)
- 1.17.1-2+deb12u4 · amd64 · bookworm
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u4 · arm64 · bookworm
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u3 · amd64 · bookworm-security
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u3 · arm64 · bookworm-security
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
[python3-unbound]Affected
Source package: [unbound]
Details (4)
- 1.17.1-2+deb12u4 · amd64 · bookworm
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u4 · arm64 · bookworm
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u3 · amd64 · bookworm-security
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u3 · arm64 · bookworm-security
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
[unbound]Affected
Details (4)
- 1.17.1-2+deb12u4 · amd64 · bookworm
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u4 · arm64 · bookworm
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u3 · amd64 · bookworm-security
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u3 · arm64 · bookworm-security
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
[unbound-anchor]Affected
Source package: [unbound]
Details (4)
- 1.17.1-2+deb12u4 · amd64 · bookworm
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u4 · arm64 · bookworm
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u3 · amd64 · bookworm-security
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u3 · arm64 · bookworm-security
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
[unbound-host]Affected
Source package: [unbound]
Details (4)
- 1.17.1-2+deb12u4 · amd64 · bookworm
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u4 · arm64 · bookworm
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u3 · amd64 · bookworm-security
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- 1.17.1-2+deb12u3 · arm64 · bookworm-security
  Affected
  dsa · unbound · debian · bookworm; dsa · unbound · debian · 12

[Debian 13 (Trixie)]

[libunbound8]Affected
Source package: [unbound]
Details (6)
- 1.22.0-2+deb13u3 · amd64 · trixie
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie-security
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.26.2-0+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
[libunbound-dev]Affected
Source package: [unbound]
Details (6)
- 1.22.0-2+deb13u3 · amd64 · trixie
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie-security
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.26.2-0+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
[python3-unbound]Affected
Source package: [unbound]
Details (6)
- 1.22.0-2+deb13u3 · amd64 · trixie
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie-security
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.26.2-0+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
[unbound]Affected
Details (6)
- 1.22.0-2+deb13u3 · amd64 · trixie
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie-security
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.26.2-0+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
[unbound-anchor]Affected
Source package: [unbound]
Details (6)
- 1.22.0-2+deb13u3 · amd64 · trixie
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie-security
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.26.2-0+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
[unbound-host]Affected
Source package: [unbound]
Details (6)
- 1.22.0-2+deb13u3 · amd64 · trixie
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie-security
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version
  Affected · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13
- 1.26.2-0+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.26.2-0+deb13u1
  dsa · unbound · debian · 13

Observed: Oct 27, 2026, 4:08:10 AM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database]