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Ubuntu Security NoticesUSN-8946-1

USN-8946-1: Unbound vulnerabilities

Severity not listed 10 CVEs Published Oct 21, 2026 at 9:48 AM UTC

Summary

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 issue to crash Unbound, resulting in a denial of service. (CVE-2026-81634)

It was discovered that Unbound incorrectly handled certain DNS responses during DNSSEC validation. A remote attacker could possibly use this issue to cause Unbound to consume resources, leading to a denial of service. (CVE-2026-85501)

It was discovered that Unbound incorrectly handled outgoing network ports. A remote attacker could possibly use this issue to crash Unbound, resulting in a denial of service. (CVE-2026-50252)

It was discovered that Unbound incorrectly handled certain DNSCrypt packets. A remote attacker could possibly use this issue to crash Unbound, resulting in a denial of service. This issue only affected Ubuntu 26.04 LTS, Ubuntu 24.04 LTS, Ubuntu 22.04 LTS, Ubuntu 20.04 LTS and Ubuntu 18.04 LTS. (CVE-2026-40691)

It was discovered that Unbound incorrectly handled certain cached DNS responses. A remote attacker could possibly use this issue to poison Unbound's cache. This issue only affected Ubuntu 26.04 LTS, Ubuntu 24.04 LTS, Ubuntu 22.04 LTS and Ubuntu 20.04 LTS. (CVE-2026-44690)

It was discovered that Unbound incorrectly handled certain DNS-over-QUIC 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. (CVE-2026-32665)

It was discovered that Unbound incorrectly handled certain EDNS options. A remote attacker could possibly use this issue to crash Unbound, resulting in a denial of service. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-55973)

Elias Heftrig, Haya Schulmann, Niklas Vogel, and Michael Waidner discovered that Unbound incorrectly handled validating DNSSEC messages. 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 18.04 LTS, Ubuntu 16.04 LTS and Ubuntu 14.04 LTS. (CVE-2023-50387)

It was discovered that Unbound incorrectly handled preparing an NSEC3 closest encloser proof. 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 18.04 LTS, Ubuntu 16.04 LTS and Ubuntu 14.04 LTS. (CVE-2023-50868)

Products covered

A separate affected-products list was not included in the collected bulletin.

Remediation

Separate remediation guidance was not included in the collected bulletin.

CVEs in this advisory 10

Updates

  1. Published by Ubuntu

    The publication date reported by the vendor.

  2. Added to SecurityAlert

    We collected the advisory from the official source.

  3. Confirmed at the source

    Our collector saw this advisory during a later source check.