CVE-2025-40908
Published: 01 June 2025
Summary
CVE-2025-40908 is a critical-severity Files or Directories Accessible to External Parties (CWE-552) vulnerability in Ingydotnet Yaml-Libyaml. Its CVSS base score is 9.1 (Critical).
Operationally, ranked in the top 40.6% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-16577
Vulnerability details
YAML-LibYAML prior to 0.903.0 for Perl uses 2-args open, allowing existing files to be modified
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Controls on authorized publication limit files and directories with nonpublic data from becoming accessible to external parties.
Controlling and documenting P2P file sharing prevents files and directories from being made accessible to external parties for unauthorized distribution.
Identifying and documenting file and directory locations allows restriction of access to external parties.
Protecting backup files ensures they are not accessible to external parties or unauthorized spheres.
Sanitizing equipment before off-site maintenance reduces the risk of files or directories containing sensitive data becoming accessible to external parties.
Policy restricts media access to authorized parties only, preventing exposure of resources to external or unauthorized actors.
Media access restrictions prevent files or directories from being accessible to external parties.
Employing and evaluating controls at documented alternate sites makes files and directories less likely to be accessible to external parties through physical or environmental weaknesses.