PatchTheCVECVE-2025-40908: YAML-LibYAML prior to 0.903.0 for Perl uses 2-args open, allowing existing files to be modified
CVE-2025-40908 is a critical-severity flaw (CVSS 9.1) affecting yaml-libyaml. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
YAML-LibYAML prior to 0.903.0 for Perl uses 2-args open, allowing existing files to be modified
Why this priority
- Critical severity
- Public exploit reference
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 9.1 (Critical) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.5% (top 59%) |
| CISA exploited list | No |
| Weakness | CWE-552 |
| Published | 2025-06-01 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2025-40908?
yaml-libyaml: upgrade to 0.903.0. Exact commands for each OS are on this page.
Is CVE-2025-40908 being exploited?
CVE-2025-40908 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2025-40908 affect?
CVE-2025-40908 affects yaml-libyaml. Severity is critical (CVSS 9.1). YAML-LibYAML prior to 0.903.0 for Perl uses 2-args open, allowing existing files to be modified
How urgent is CVE-2025-40908?
Priority 52/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action