CVE catalog

CVE-2026-85501

Severity: Medium · CVSS 5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Published: Sep 15, 2026, 10:00:00 PM UTC
Updated: Sep 16, 2026, 9:17:06 AM UTC
Source: [NVD] · [CVE record]
EPSS: 0.48% · Oct 25, 2026

Novel vulnerabilities to launch algorithmic complexity attacks on DNSSEC have been researched under the term 'ReTrap'. These result in degradation of service when malicious zones are used to serve the algorithmic complexity vulnerabilities. NLnet Labs Unbound up to and including 1.26.0 is vulnerable to some of them. TagTrap, where the triple(Zone, Algo, KeyTag) matching mechanism introduces a significant attack vector when resolvers handle malicious responses containing numerous mismatched DNSKEY, RRSIG, and DS record. DelegationTrap, where constructing the chain-of-trust requires iterative validation of DNSKEY and DS records from the root zone downward. For deeply nested domains, this results in significant computational overhead. NsecTrap, where responses with excessive invalid NSEC records compel the resolver to validate each one. AdditionalTrap, where Unbound by default would try to DNSSEC validate the ADDITIONAL section as well. This can be exploited to waste validation resources by malicious users.

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
Cpe	unbound	Not reported	`1.26.1`	fixed
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`	fixed
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`	fixed
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`	fixed
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`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	unbound	source	sid	`1.26.1-1`	not yet assigned	Not reported	Not reported
Debian	unbound	source	forky	`1.26.1-1`	not yet assigned	Not reported	Not reported
Debian	unbound	source	trixie	`1.26.1-0+deb13u1`	not yet assigned	Not reported	Not reported
Debian	unbound	source	bookworm	`(unfixed)`	not yet assigned	Not reported	Not reported
Cpe	unbound	cpe	Not reported	`1.26.1`	Not reported	NVD-CVE-2026-85501	Not reported
Ubuntu	unbound	deb	pro	`1.9.4-2ubuntu1.11+esm3`	Not reported	UBUNTU-CVE-2026-85501	Not reported
Ubuntu	unbound	deb	22.04	`1.13.1-1ubuntu5.17`	Not reported	UBUNTU-CVE-2026-85501	Not reported
Ubuntu	unbound	deb	24.04	`1.19.2-1ubuntu3.12`	Not reported	UBUNTU-CVE-2026-85501	Not reported
Ubuntu	unbound	deb	26.04	`1.24.2-1ubuntu2.4`	Not reported	UBUNTU-CVE-2026-85501	Not reported

OpenFactory catalog packages

[Debian 12 (Bookworm)]

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

[Debian 13 (Trixie)]

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

Observed: Oct 27, 2026, 6:27:24 AM UTC

References

[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]