Red Hat Security Advisory: perl-YAML-LibYAML security update
Affects Red Hat perl-YAML-LibYAMLSource GCVE Database
Not known to be exploited · CVSS 9.1 Critical : upgrade the Red Hat redhat/perl-YAML-LibYAML package to 9.4.1 as a priority.
Data as of 26 Oct 2026, 11:07 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 39% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 9.4.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 1 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade the Red Hat redhat/perl-YAML-LibYAML package to 9.4.1.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Red Hatredhat/perl-YAML-LibYAMLpkg:rpm/redhat/perl-YAML-LibYAMLOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
Kirill Siminov's "libyaml" is arguably the best YAML implementation. The C library is written precisely to the YAML 1.1 specification. It was originally bound to Python and was later bound to Ruby. Security Fix(es): * yaml-libyaml: LibYAML Perl File Modification Vulnerability (CVE-2025-40908) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.