CVE-2026-4177CWE-122

YAML::Syck versions through 1.36 for Perl has several potential security vulnerabilities including a high-severity heap buffer overflow in the YAML emitter

Critical · published March 16, 2026

CVSS v3.1
9.1
EPSS
1%
Percentile
49.3
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
9.1 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00625 · 49.3th percentile
Weakness
CWE-122 · Heap-based Buffer Overflow
Published
2026-03-16T22:30Z
EPSS history
Timeline
  • 16 MAR 22:30Z
    YAML::Syck versions through 1.36 for Perl has several potential security vulnerabilities including a high-severity heap buffer overflow in the YAML emitter
    cvelistv5