Vulnerability in Ingydotnet Yaml-Libyaml

CVE-2025-40908

YAML-LibYAML prior to 0.903.0 for Perl uses 2-args open, allowing existing files to be modified

EPSS: 0.004 (31.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-40908?
CVE-2025-40908 is a critical-severity vulnerability in Ingydotnet Yaml-Libyaml, classified under Files or Directories Accessible to External Parties. CVSS score: 9.1/10. Published 2025-06-01.
How severe is CVE-2025-40908?
Critical severity. CVSS v3 base score is 9.1 out of 10.
Is CVE-2025-40908 known to be exploited?
2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.