CVE catalog

CVE-2026-44390

NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability when handling replies with very large RRsets that Unbound needs to perform name compression for. Malicious upstream responses

[CVE catalog]

Severity
High · CVSS 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
Source
[NVD] · [CVE record]
EPSS
0.65% · Oct 25, 2026

NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability when handling replies with very large RRsets that Unbound needs to perform name compression for. Malicious upstream responses with very large RRsets with records that don't share a suffix above the root can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. An adversary can exploit the vulnerability by querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. A compression limit was introduced in 1.21.1 for this but it didn't account for the case where records would not share any suffix above the root. That causes Unbound to go in a different code path because of the compression tree lookup failure and eventually not increment the compression counter for those operations. Unbound 1.25.1 contains a patch with a fix that increments the compression counter regardless of the compression tree lookup. This is a complement fix to CVE-2024-8508.

Vulnerable and fixed packages

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

DistributionPackageReleaseVersionStatus
Debianunboundsid1.26.2-1fixed
Debianunboundforky1.26.2-1fixed
Debianunboundtrixie1.22.0-2+deb13u3fixed
Debianunboundtrixie-security1.26.2-0+deb13u1fixed
Debianunboundbookworm1.17.1-2+deb12u4vulnerable
Debianunboundbookworm-security1.17.1-2+deb12u3vulnerable
CpeunboundNot reported1.19.2-1ubuntu3.8fixed
Cpelibunbound-devNot reported1.19.2-1ubuntu3.8fixed
Cpelibunbound8Not reported1.19.2-1ubuntu3.8fixed
Cpepython3-unboundNot reported1.19.2-1ubuntu3.8fixed
Cpeunbound-anchorNot reported1.19.2-1ubuntu3.8fixed
Cpeunbound-hostNot reported1.19.2-1ubuntu3.8fixed
CpeunboundNot reportedNot reportedvulnerable
CpeunboundNot reported1.25.1fixed
CpeunboundNot reported1.25.1fixed
Ubuntuunboundpro1.9.0-2ubuntu1vulnerable
Ubuntuunboundpro1.9.0-2ubuntu2vulnerable
Ubuntuunboundpro1.9.4-2vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1.1vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1.2vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1.3vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1.4vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1.5vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1.6vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1.8vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1.9vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1.11vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1.11+esm1vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1.11+esm2vulnerable
Ubuntuunboundpro1.9.4-2ubuntu1.11+esm3vulnerable
Ubuntuunbound22.041.13.1-1ubuntu1vulnerable
Ubuntuunbound22.041.13.1-1ubuntu3vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.1vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.2vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.3vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.4vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.5vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.7vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.8vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.10vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.11vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.12vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.13vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.14vulnerable
Ubuntuunbound22.041.13.1-1ubuntu5.15fixed
Ubuntuunbound24.041.17.1-2vulnerable
Ubuntuunbound24.041.18.0-2ubuntu1vulnerable
Ubuntuunbound24.041.18.0-2ubuntu2vulnerable
Ubuntuunbound24.041.19.1-1ubuntu1vulnerable
Ubuntuunbound24.041.19.2-1ubuntu1vulnerable
Ubuntuunbound24.041.19.2-1ubuntu3vulnerable
Ubuntuunbound24.041.19.2-1ubuntu3.1vulnerable
Ubuntuunbound24.041.19.2-1ubuntu3.2vulnerable
Ubuntuunbound24.041.19.2-1ubuntu3.3vulnerable
Ubuntuunbound24.041.19.2-1ubuntu3.4vulnerable
Ubuntuunbound24.041.19.2-1ubuntu3.5vulnerable
Ubuntuunbound24.041.19.2-1ubuntu3.6vulnerable
Ubuntuunbound24.041.19.2-1ubuntu3.7vulnerable
Ubuntuunbound24.041.19.2-1ubuntu3.8fixed
Ubuntuunbound25.101.22.0-1ubuntu1vulnerable
Ubuntuunbound25.101.22.0-2ubuntu1vulnerable
Ubuntuunbound25.101.22.0-2ubuntu2vulnerable
Ubuntuunbound25.101.22.0-2ubuntu2.1vulnerable
Ubuntuunbound25.101.22.0-2ubuntu2.2vulnerable
Ubuntuunbound25.101.22.0-2ubuntu2.3fixed
Ubuntuunbound26.041.22.0-2ubuntu2vulnerable
Ubuntuunbound26.041.22.0-2ubuntu4vulnerable
Ubuntuunbound26.041.24.2-1ubuntu1vulnerable
Ubuntuunbound26.041.24.2-1ubuntu2vulnerable
Ubuntuunbound26.041.24.2-1ubuntu2.1fixed
Alpineunbound3.221.25.2-r0fixed
Alpineunbound3.231.25.2-r0fixed
Alpineunbound3.241.25.1-r0fixed

Fixed-version evidence

DistributionPackageTypeReleaseFixed versionUrgencyOriginBugs
Debianunboundsourcesid1.25.1-1not yet assignedNot reported[1137187]
Debianunboundsourceforky1.25.1-1not yet assignedNot reported[1137187]
Debianunboundsourcetrixie1.22.0-2+deb13u3not yet assignedNot reported[1137187]
Debianunboundsourcebookworm(unfixed)not yet assignedNot reported[1137187]
CpeunboundcpeNot reported1.19.2-1ubuntu3.8Not reportedNot reportedNot reported
Cpelibunbound-devcpeNot reported1.19.2-1ubuntu3.8Not reportedNot reportedNot reported
Cpelibunbound8cpeNot reported1.19.2-1ubuntu3.8Not reportedNot reportedNot reported
Cpepython3-unboundcpeNot reported1.19.2-1ubuntu3.8Not reportedNot reportedNot reported
Cpeunbound-anchorcpeNot reported1.19.2-1ubuntu3.8Not reportedNot reportedNot reported
Cpeunbound-hostcpeNot reported1.19.2-1ubuntu3.8Not reportedNot reportedNot reported
CpeunboundcpeNot reported1.25.1Not reportedNot reportedNot reported
CpeunboundcpeNot reported1.25.1Not reportedNVD-CVE-2026-44390Not reported
Ubuntuunbounddeb22.041.13.1-1ubuntu5.15Not reportedUBUNTU-CVE-2026-44390Not reported
Ubuntuunbounddeb24.041.19.2-1ubuntu3.8Not reportedUBUNTU-CVE-2026-44390Not reported
Ubuntuunbounddeb25.101.22.0-2ubuntu2.3Not reportedUBUNTU-CVE-2026-44390Not reported
Ubuntuunbounddeb26.041.24.2-1ubuntu2.1Not reportedUBUNTU-CVE-2026-44390Not reported
Alpineunboundapk3.221.25.2-r0Not reportedALPINE-CVE-2026-44390Not reported
Alpineunboundapk3.231.25.2-r0Not reportedALPINE-CVE-2026-44390Not reported
Alpineunboundapk3.241.25.1-r0Not reportedALPINE-CVE-2026-44390Not reported

[Debian bug #1137187]

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]Fixed

    Source package: [unbound]

    Details (6)

    • 1.22.0-2+deb13u3 · amd64 · trixie

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · arm64 · trixie

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · arm64 · trixie-security

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.26.2-0+deb13u1 · amd64 · trixie-security

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

  • [libunbound-dev]Fixed

    Source package: [unbound]

    Details (6)

    • 1.22.0-2+deb13u3 · amd64 · trixie

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · arm64 · trixie

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · arm64 · trixie-security

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.26.2-0+deb13u1 · amd64 · trixie-security

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

  • [python3-unbound]Fixed

    Source package: [unbound]

    Details (6)

    • 1.22.0-2+deb13u3 · amd64 · trixie

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · arm64 · trixie

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · arm64 · trixie-security

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.26.2-0+deb13u1 · amd64 · trixie-security

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

  • [unbound]Fixed
    Details (6)

    • 1.22.0-2+deb13u3 · amd64 · trixie

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · arm64 · trixie

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · arm64 · trixie-security

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.26.2-0+deb13u1 · amd64 · trixie-security

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

  • [unbound-anchor]Fixed

    Source package: [unbound]

    Details (6)

    • 1.22.0-2+deb13u3 · amd64 · trixie

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · arm64 · trixie

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · arm64 · trixie-security

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.26.2-0+deb13u1 · amd64 · trixie-security

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

  • [unbound-host]Fixed

    Source package: [unbound]

    Details (6)

    • 1.22.0-2+deb13u3 · amd64 · trixie

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · arm64 · trixie

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.22.0-2+deb13u3 · arm64 · trixie-security

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

    • 1.26.2-0+deb13u1 · amd64 · trixie-security

      Fixed · Fixed: 1.22.0-2+deb13u3

      nvd · unbound · debian · 13

Observed:

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] · [Ubuntu Security Notices (USN)]