CPANSA-YAML-Syck-2026-5089: YAML-Syck vulnerability

Publisher giterlizzi Document category csaf_security_advisory
Initial release date 2026-05-12T00:00:00 Engine CSAF Perl Toolkit 0.26
Current release date 2026-05-12T00:00:00 Build Date
Current version 1 Status final
CVSS v3.1 Base Score 7.3 Severity
Original language Language en
Also referred to

Vulnerability Description

YAML::Syck versions before 1.38 for Perl has an out-of-bounds read. The base60 (sexagesimal) parsing code in perl_syck.h has a buffer underflow bug in both int#base60 and float#base60 handlers. When processing the leftmost segment of a colon-separated value (e.g., the 1 in 1:30:45), the inner while loop can decrement a pointer past the start of the string buffer: while ( colon >= ptr && *colon != ':' ) { colon--; } if ( *colon == ':' ) *colon = '\0'; // colon may be ptr-1 here When no colon is found (final/leftmost segment), colon becomes ptr-1, and the subsequent *colon dereference reads one byte before the allocated buffer.

Vulnerabilities

CVE-2026-5089

Vulnerability Description

YAML::Syck versions before 1.38 for Perl has an out-of-bounds read.

The base60 (sexagesimal) parsing code in perl_syck.h has a buffer underflow bug in both int#base60 and float#base60 handlers. When processing the leftmost segment of a colon-separated value (e.g., the 1 in 1:30:45), the inner while loop can decrement a pointer past the start of the string buffer:

while ( colon >= ptr && *colon != ':' )
{
colon--;
}
if ( *colon == ':' ) *colon = '\0'; // colon may be ptr-1 here

When no colon is found (final/leftmost segment), colon becomes ptr-1, and the subsequent *colon dereference reads one byte before the allocated buffer.

Weakness CWE-124 : Buffer Underwrite ('Buffer Underflow')

Product status

Known affected
Product Score
YAML-Syck less than 1.38
CVSS Version CVSS Vector CVSS Base Score CVSS Base Severity
3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L 7.3 High
Fixed

giterlizzi

Namespace: https://github.com/giterlizzi/

gdt@cpan.org

References

Revision history

Version Date of the revision Summary of the revision
1 Tue May 12 00:00:00 2026 First release

Sharing rules

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