Debian dla-4525 : libyaml-syck-perl - security update

critical Nessus Plugin ID 307673

Synopsis

The remote Debian host is missing one or more security-related updates.

Description

The remote Debian 11 host has a package installed that is affected by multiple vulnerabilities as referenced in the dla-4525 advisory.

- ------------------------------------------------------------------------- Debian LTS Advisory DLA-4525-1 [email protected] https://www.debian.org/lts/security/ Andrej Shadura April 09, 2026 https://wiki.debian.org/LTS
- -------------------------------------------------------------------------

Package : libyaml-syck-perl Version : 1.34-1+deb11u1 CVE ID : CVE-2025-11683 CVE-2026-4177

Brief introduction

CVE-2025-11683

Missing null terminators in token.c leads to but-of-bounds read which allows adjacent variable to be read. The issue is seen with complex YAML files with a hash of all keys and empty values.

CVE-2026-4177

Several security vulnerabilities including a high-severity heap buffer overflow in the YAML emitter. The heap overflow occurs when class names exceed the initial 512-byte allocation. The base64 decoder could read past the buffer end on trailing newlines. strtok mutated n->type_id in place, corrupting shared node data. A memory leak occurred in syck_hdlr_add_anchor when a node already had an anchor. The incoming anchor string 'a' was leaked on early return.

For Debian 11 bullseye, these problems have been fixed in version 1.34-1+deb11u1.

We recommend that you upgrade your libyaml-syck-perl packages.

For the detailed security status of libyaml-syck-perl please refer to its security tracker page at:
https://security-tracker.debian.org/tracker/libyaml-syck-perl

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS

Tenable has extracted the preceding description block directly from the Debian 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

Upgrade the libyaml-syck-perl packages.

Plugin Details

Severity: Critical

ID: 307673

File Name: debian_DLA-4525.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Debian Local Security Checks

Published: 4/21/2026

Updated: 4/21/2026

Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.0

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-2026-4177

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:debian:debian_linux:11.0, p-cpe:/a:debian:debian_linux:libyaml-syck-perl

Required KB Items: Host/local_checks_enabled, Host/Debian/release, Host/Debian/dpkg-l

Exploit Ease: No known exploits are available

Patch Publication Date: 4/9/2026

Vulnerability Publication Date: 10/16/2025

Reference Information

CVE: CVE-2025-11683, CVE-2026-4177

Detections

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