Unbound Vulnerabilities — Ubuntu Security Update (USN-8946-2)
USN-8946-2 extends the Unbound security fixes from USN-8946-1 to Ubuntu 26.10; the original notice covered Ubuntu 26.04 LTS down to 14.04 LTS. Unbound incorrectly handled certain TCP connections, allowing a remote attacker to make the DNS resolver consume resources until it denies service (CVE-2026-80225, per the notice this affected 26.04/24.04/22.04/20.04 LTS). The notice lists 8 distinct CVE identifiers for the family, with CVSS 5.3 and CWE-770 in this advisory's data.
SharedLicense lisansı altında bunun anlamı
DNS resolvers are infrastructure: a resource-exhaustion DoS against Unbound degrades every lookup that depends on it. Ubuntu 26.10 hosts running Unbound should take this follow-up package update and restart the service.
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 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)
Sıkça Sorulan Sorular
What is the difference between USN-8946-1 and USN-8946-2?
What can an attacker do against a vulnerable Unbound?
How is it applied?
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