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TencentOS Server 2: gnutls (TSSA-2026:0816)

critical Nessus Plugin ID 333142

Synopsis

The remote TencentOS Server 2 host is missing one or more security updates.

Description

The version of Tencent Linux installed on the remote TencentOS Server 2 host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:0816 advisory.

 Package updates are available for TencentOS Server 2 that fix the following vulnerabilities:

 CVE-2026-33845:
 A flaw in GnuTLS DTLS handshake parsing allows malformed fragments with zero length and non-zero offset, leading to an integer underflow during reassembly and resulting in an out-of-bounds read. This issue is remotely exploitable and may cause information disclosure or denial of service.

 CVE-2026-33846:
 A heap buffer overflow vulnerability exists in the DTLS handshake fragment reassembly logic of GnuTLS. The issue arises in merge_handshake_packet() where incoming handshake fragments are matched and merged based solely on handshake type, without validating that the message_length field remains consistent across all fragments of the same logical message. An attacker can exploit this by sending crafted DTLS fragments with conflicting message_length values, causing the implementation to allocate a buffer based on a smaller initial fragment and subsequently write beyond its bounds using larger, inconsistent fragments. Because the merge operation does not enforce proper bounds checking against the allocated buffer size, this results in an out-of-bounds write on the heap. The vulnerability is remotely exploitable without authentication via the DTLS handshake path and can lead to application crashes or potential memory corruption.

 CVE-2026-42009:
 A flaw was found in gnutls. A remote attacker could exploit an issue in the Datagram Transport Layer Security (DTLS) packet reordering logic. The comparator function, responsible for ordering DTLS packets by sequence numbers, did not correctly handle packets with duplicate sequence numbers. This could lead to unstable packet ordering or undefined behavior, resulting in a denial of service.

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-20260816.xml

Plugin Details

Severity: Critical

ID: 333142

File Name: tencentos_TSSA_2026_0816.nasl

Version: 1.1

Type: Local

Published: 8/6/2026

Updated: 8/6/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.3

Percentile: 53.64

CVSS v2

Risk Factor: High

Base Score: 9.4

Temporal Score: 7

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

CVSS Score Source: CVE-2026-33845

CVSS v3

Risk Factor: Critical

Base Score: 9.1

Temporal Score: 7.9

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

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

Vulnerability Information

CPE: cpe:/o:tencent:tencentos_server:2, p-cpe:/a:tencent:tencentos_server:gnutls

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: 7/1/2026

Vulnerability Publication Date: 4/30/2026

Reference Information

CVE: CVE-2026-33845, CVE-2026-33846, CVE-2026-42009

IAVA: 2026-A-0405