Detections
Analytics

TencentOS Server 3: unbound (TSSA-2026:0887)

high Nessus Plugin ID 340978

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 multiple vulnerabilities as referenced in the TSSA-2026:0887 advisory.

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

 CVE-2026-40622:
 A flaw was found in NLnet Labs Unbound. A remote attacker, by controlling a malicious domain (a ghost zone) and querying a vulnerable Unbound server, could exploit a vulnerability related to ghost domain names attacks. This could allow the attacker to overwrite cached Name Server (NS) records, extending the ghost domain window by up to one cached Time To Live (TTL) value. This manipulation could lead to cache poisoning, potentially causing the Unbound server to serve incorrect or malicious DNS information.

 CVE-2026-41292:
 A flaw was found in Unbound. A remote attacker can exploit this vulnerability by sending queries with an excessive number of EDNS (Extension Mechanisms for DNS) options. This can cause Unbound threads to be held hostage while parsing and creating internal data structures for these options. Coordinated attacks can lead to resource exhaustion, resulting in a degradation of service or a denial of service (DoS) for legitimate users.

 CVE-2026-42534:
 A flaw was found in Unbound. An adversary who can query a vulnerable Unbound instance and control a slow or malicious domain name server can exploit a vulnerability in the jostle logic. This flaw allows retransmitted queries to renew the age of slow-running queries, preventing them from being identified as aged and replaced. This can degrade Unbound's resolution performance, potentially leading to a denial of resolution service through coordinated attacks.

 CVE-2026-44390:
 A flaw was found in Unbound. A remote attacker can exploit this vulnerability by sending specially crafted DNS responses containing very large Resource Record Sets (RRsets) that require name compression. This can cause Unbound to spend a significant amount of time processing these responses, leading to degraded performance and potentially a denial of service (DoS) for legitimate users.

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

Note that Nessus has not tested for these issues 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-20260887.xml

Plugin Details

Severity: High

ID: 340978

File Name: tencentos_TSSA_2026_0887.nasl

Version: 1.1

Type: Local

Published: 8/26/2026

Updated: 8/26/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.75

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 5.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:C/A:N

CVSS Score Source: CVE-2026-40622

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

CVSS v4

Risk Factor: High

Base Score: 8.7

Threat Score: 6.6

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS Score Source: CVE-2026-41292

Vulnerability Information

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

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

Exploit Ease: No known exploits are available

Patch Publication Date: 7/9/2026

Vulnerability Publication Date: 5/20/2026

Reference Information

CVE: CVE-2026-40622, CVE-2026-41292, CVE-2026-42534, CVE-2026-44390