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Vulnerability · Published May 12, 2026 · Assigned by CPANSec

CVE-2026-5089YAML::Syck versions before 1.38 for Perl has an out-of-bounds read

High 7.3

In plain English

A high-severity security flaw in YAML::Syck from TODDR. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 35% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.3High
Exploit odds (30 days)0.4%top 65.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12libyaml-syck-perl1.34-2+deb12u3DEBIAN-CVE-2026-5089
Debian:13libyaml-syck-perl1.34-2+deb13u3DEBIAN-CVE-2026-5089
Debian:14libyaml-syck-perl1.36-3DEBIAN-CVE-2026-5089
Ubuntu:25.10libyaml-syck-perlno fix listedUBUNTU-CVE-2026-5089
Ubuntu:26.04:LTSlibyaml-syck-perlno fix listedUBUNTU-CVE-2026-5089
Ubuntu:26.10libyaml-syck-perlno fix listedUBUNTU-CVE-2026-5089

Affected products (as reported)

VendorProductVersions
TODDR YAML::Syck 0 – before 1.38

Weakness: CWE-124 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

References