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Fencer Intel
high 7.3

CVE-2026-5089 json

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

published 5mo ago modified 16d ago also EUVD-2026-29543

cvss
7.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 35%
public exploits
0
none known

Summary

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.

Patch / fix

  • TODDR YAML::Syck 1.38
  • libyaml-syck-perl Debian 12 1.34-2+deb12u3
  • libyaml-syck-perl Debian 13 1.34-2+deb13u3
  • libyaml-syck-perl Debian 14 1.36-3

debian advisories DEBIAN-CVE-2026-5089

  • perl-YAML-Syck openSUSE Leap 16.0 1.450.0-bp160.2.1
  • perl-YAML-Syck openSUSE Tumbleweed 1.450.0-4.1

opensuse advisories openSUSE-SU-2026:20938-1openSUSE-SU-2026:10846-1

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-5089 updated cvss 4.0

perl-YAML-Syck: perl-YAML-Syck: Information disclosure via out-of-bounds read in base60 parsing

  • Red Hat Enterprise Linux 6 perl-YAML-Syck Red Hat Enterprise Linux 8 perl-YAML-Syck
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
5mo ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/cpan-authors/YAML-Syck/issues/132 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
CNA 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Affected products

  • TODDR YAML::Syck

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.