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TencentOS Server 3: unbound (TSSA-2025:0694)

high Nessus Plugin ID 253500

Synopsis

The remote TencentOS Server 3 host is missing one or more security updates.

Description

The version of Tencent Linux installed on the remote TencentOS Server 3 host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the TSSA-2025:0694 advisory.

 Package updates are available for TencentOS Server 3 that fix the following vulnerabilities:

 CVE-2025-5994:
 A multi-vendor cache poisoning vulnerability named 'Rebirthday Attack' has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., '--enable-subnet', AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the 'send-client-subnet', 'client-subnet-zone' or 'client-subnet- always-forward' options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies.

Tenable has extracted the preceding description block directly from the Tencent Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Update the affected packages.

See Also

https://mirrors.tencent.com/tlinux/errata/tssa-20250694.xml

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2025-5994

Plugin Details

Severity: High

ID: 253500

File Name: tencentos_TSSA_2025_0694.nasl

Version: 1.1

Type: local

Published: 8/21/2025

Updated: 8/21/2025

Supported Sensors: Nessus

Vulnerability Information

CPE: cpe:/o:tencent:tencentos_server:3, p-cpe:/a:tencent:tencentos_server:unbound

Required KB Items: Host/local_checks_enabled, Host/etc/os-release, Host/TencentOS/rpm-list, Host/cpu

Exploit Ease: No known exploits are available

Patch Publication Date: 7/28/2025

Vulnerability Publication Date: 7/28/2025