🛡️ CVE-2026-4177 on Debian — libyaml-syck-perl

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

YAML::Syck versions through 1.36 for Perl has several potential 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.

Distribution advisory

This page covers CVE-2026-4177 as tracked by Debian, for the package libyaml-syck-perl. The fix is available in version 1.36-2; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity none, availability high.

Weakness class

DEBIAN-CVE-2026-4177 is classified as CWE-122: Heap-based Buffer Overflow. A write past the end of a heap allocation corrupts allocator metadata or neighbouring objects.

Affected software

DEBIAN-CVE-2026-4177 is recorded against 1 package.

  • libyaml-syck-perl (fixed in 1.36-2)

Timeline and source

Published on 16 March 2026 and last revised on 4 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

CVE-2026-4177 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-03-16
Updated 2026-08-20
Modified 2026-08-04
Fix URL N/A

Affected Packages

Software From version Fixed in
libyaml-syck-perl — 1.36-2

Exploit Protection

Are you running libyaml-syck-perl?

DEBIAN-CVE-2026-4177 carries CVSS 9.1 Critical rating. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

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