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Ubuntu 26.04 LTS NSD Critical Buffer Overflow and DoS Alert 8474

Ubuntu 26.04 LTS NSD Critical Buffer Overflow and DoS Alert 8474

Linuxsecurity •LinuxSecurity Advisories • June 25, 2026

NSD could be made to crash or run programs if it received specially crafted network traffic. Software Description: - nsd: Several security issues were fixed in NSD, including a stack-based buffer overflow in APL resource record handling, a heap overflow in SVCB resource record handling, a use-after-free in TLS connection error logging, and a TLS authentication bypass for zone transfers. Details: It was discovered that NSD incorrectly handled APL resource records with an address length larger than permitted for the address family. A remote attacker could use this to cause a stack-based buffer overflow when the zone is written to disk, potentially executing arbitrary code with the privileges of the NSD server. (CVE-2026-12246) It was discovered that NSD incorrectly handled SVCB resource records. A remote attacker could use this to cause a heap overflow, potentially executing arbitrary code with the privileges of the NSD server. This issue only affected Ubuntu 26.04 LTS. (CVE-2026... Read the Full Advisory

NSD could be made to crash or run programs if it received specially

crafted network traffic.

Software Description:

- nsd: Several security issues were fixed in NSD, including a stack-based buffer overflow in APL resource record handling, a heap overflow in SVCB resource record handling, a use-after-free in TLS connection error logging, and a TLS authentication bypass for zone transfers.

It was discovered that NSD incorrectly handled APL resource records with an

address length larger than permitted for the address family. A remote attacker

could use this to cause a stack-based buffer overflow when the zone is written

to disk, potentially executing arbitrary code with the privileges of the NSD

server. (CVE-2026-12246)

It was discovered that NSD incorrectly handled SVCB resource records. A remote

attacker could use this to cause a heap overflow, potentially executing

arbitrary code with the privileges of the NSD server. This issue only affected

Ubuntu 26.04 LTS. (CVE-2026...

The problem can be corrected by updating your system to the following package versions: Ubuntu 26.04 LTS nsd 4.14.0-1ubuntu0.1~esm1 Available with Ubuntu Pro Ubuntu 24.04 LTS nsd 4.8.0-1ubuntu0.1~esm1 Available with Ubuntu Pro Ubuntu 22.04 LTS nsd 4.3.9-1ubuntu0.1~esm1 Available with Ubuntu Pro Ubuntu 20.04 LTS nsd 4.1.26-1ubuntu0.1~esm1 Available with Ubuntu Pro Ubuntu 18.04 LTS nsd 4.1.17-1ubuntu0.1~esm1 Available with Ubuntu Pro Ubuntu 16.04 LTS nsd 4.1.7-1ubuntu0.1~esm1 Available with Ubuntu Pro nsd3 4.1.7-1ubuntu0.1~esm1 Available with Ubuntu Pro In general, a standard system update will make all the necessary changes.

CVE-2026-12244, CVE-2026-12245, CVE-2026-12246, CVE-2026-12490

Ubuntu Security Notice USN-8474-1

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