CentOS Linux 7 [TuxCare] Security Update: gnutls / gnutls-c++ / gnutls-dane / gnutls-devel / gnutls-utils Multiple Vulnerabilities (CENTOS7:CLSA-2026:1780925342)

high Nessus Plugin ID 351685

Synopsis

The CentOS Linux host is missing one or more security updates.

Description

The CentOS Linux 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare CENTOS7:CLSA-2026:1780925342 advisory.

- 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-2026-33846)

- 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. (CVE-2026-42009)

- A flaw was found in gnutls. A remote attacker could exploit this vulnerability by presenting a specially crafted certificate that contains Uniform Resource Identifier (URI) or Service (SRV) Subject Alternative Names (SANs). This could cause the certificate validation process to incorrectly fall back to checking DNS hostnames against the Common Name (CN), potentially allowing the attacker to spoof legitimate services or intercept sensitive information. (CVE-2026-42012)

- A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name (SAN) could cause the validation process to incorrectly fall back to checking the Common Name (CN) field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to spoofing or man-in-the-middle attacks. (CVE-2026-42013)

- A flaw was found in libgnutls. A remote attacker, by sending an extremely short premaster secret during an RSA key exchange to a server using an RSA key backed by a PKCS#11 token, could trigger a short heap overread. This memory corruption vulnerability could lead to information disclosure. (CVE-2026-5260)

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 based on the guidance in TuxCare advisory CENTOS7:CLSA-2026:1780925342.

Plugin Details

Severity: High

ID: 351685

File Name: tuxcare_centos_7_CLSA-2026-1780925342.nasl

Version: 1.1

Type: Local

Agent: unix

Family: CentOS Local Security Checks

Published: 9/30/2026

Updated: 9/30/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.5

Percentile: 52.04

Vendor

Vendor Severity: Important

CVSS v2

Risk Factor: High

Base Score: 8.5

Temporal Score: 6.3

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

CVSS Score Source: CVE-2026-5260

CVSS v3

Risk Factor: High

Base Score: 8.2

Temporal Score: 7.1

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

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

Vulnerability Information

Required KB Items: Host/local_checks_enabled, Host/CentOS/release, Host/CentOS/rpm-list, Host/OS/extended-third-party

Exploit Ease: No known exploits are available

Patch Publication Date: 6/8/2026

Vulnerability Publication Date: 4/30/2026

Reference Information

CVE: CVE-2026-33846, CVE-2026-42009, CVE-2026-42012, CVE-2026-42013, CVE-2026-5260

CLSA: 2026:1780925342

Detections

Analytics