Advisories

Unbound vulnerabilities

USN-8946-1 fixed vulnerabilities in Unbound in Ubuntu 26.04 LTS, Ubuntu 24.04 LTS, Ubuntu 22.04 LTS, Ubuntu 20.04 LTS, Ubuntu 18.04 LTS, Ubuntu 16.04 LTS, and Ubuntu 14.04 LTS. This update provides the corresponding update for Ubuntu 26.10. Original advisory details: It was discovered that Unbound incorrectly handled certain TCP connections. A remote attacker could possibly use this issue to cause Unbound to consume resources, leading to a denial of service. This issue only affected Ubuntu 26.04 LTS, Ubuntu 24.04 LTS, Ubuntu 22.04 LTS and Ubuntu 20.04 LTS. (CVE-2026-80225) It was discovered that Unbound incorrectly handled certain DNS responses. A remote attacker could possibly use this issu

Read at Ubuntu Security Notices

Vendor

Canonical

Product

Ubuntu, dnsmasq / Unbound / PowerDNS

EPSS

0.003 (p21)

Exposure class

Operating system, Edge / VPN / firewall

• Ubuntu Security Notices (ubuntu.com)
• CVE-2026-80225 on this site · NVD · CVE.org · Vulnpedia
• CVE-2026-81634 on this site · NVD · CVE.org · Vulnpedia
• CVE-2026-85501 on this site · NVD · CVE.org · Vulnpedia
• CVE-2026-50252 on this site · NVD · CVE.org · Vulnpedia
• CVE-2026-40691 on this site · NVD · CVE.org · Vulnpedia

Other items that share a CVE or were clustered with this one.

1. 21
   CVE NVD 16 Sep 2026

   Novel vulnerabilities to launch algorithmic complexity attacks on DNSSEC have been researched under the term 'ReTrap'.

   CVSS 5.3 CVE-2026-85501
2. 28
   CVE NVD 16 Sep 2026

   In NLnet Labs Unbound up to and including 1.26.0, a 255 length query name with a large TCP response can lead to a heap buffer overflow during the…

   CVSS 7.5 CVE-2026-81634 Canonical
3. 21
   CVE NVD 16 Sep 2026

   In NLnetLabs Unbound up to and including 1.26.0, a degradation of service vulnerability is present in the TCP/DoT reading procedure where there is no…

   CVSS 5.3 CVE-2026-80225
4. 20
   Advisory MSRC 23 Jul 2026

   CVE-2026-50252 Possible cache poisoning attack by mapping source port population per thread

   CVE-2026-50252 Microsoft
5. 20
   Advisory MSRC 23 Jul 2026

   CVE-2026-32665 Remote DNS-over-QUIC denial of service due to `quic-size` budget bypass

   CVE-2026-32665 Microsoft
6. 20
   Advisory MSRC 23 Jul 2026

   CVE-2026-40691 Packet of death for DNSCrypt over TCP

   CVE-2026-40691 Microsoft
7. 20
   Advisory MSRC 23 Jul 2026

   CVE-2026-44690 Cross-zone wildcard cache poisoning via RRSIG.labels manipulation

   CVE-2026-44690 Microsoft
8. 20
   Advisory MSRC 23 Jul 2026

   CVE-2026-55973 'dns-error-reporting: yes' leads to stack buffer overflow

   CVE-2026-55973 Microsoft
9. 34
   CVE NVD 22 Jul 2026

   In NLnet Labs Unbound 1.23.0 up to and including 1.25.1, when 'dns-error-reporting: yes' is set, the EDNS Report-Channel option (code 18) from the…

   CVSS 7.5 CVE-2026-55973
10. 24
    CVE NVD 22 Jul 2026

    In NLnet Labs Unbound 1.4.22 up to and including 1.25.1, UDP source port is randomized and intended to serve as a secret value that increases the…

    CVE-2026-50252
11. 34
    CVE NVD 22 Jul 2026

    In NLnet Labs Unbound 1.7.0 up to and including 1.25.1, insufficient validation of the RRSIG.Labels field combined with premature cache writes during…

    CVSS 7.5 CVE-2026-44690
12. 34
    CVE NVD 22 Jul 2026

    In Unbound 1.9.0 up to and including 1.25.1, when a DNSCrypt query is received over TCP, the routine that encrypts the reply in place fails to bound…

    CVSS 7.5 CVE-2026-40691
13. 34
    CVE NVD 22 Jul 2026

    In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, when downstream DNS-over-QUIC (DoQ) is enabled, the first two bidirectional streams on a new…

    CVSS 7.5 CVE-2026-32665