CVE-2026-0966
Libssh: libssh: denial of service via zero-length input in ssh_get_hexa()
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.
Fixes and workarounds
Workaround
Applications using libssh should avoid passing zero-length input to ssh_get_hexa(), ssh_get_fingerprint_hash(), and ssh_print_hexa(). For the remotely reachable GSSAPI authentication path, disable GSSAPI authentication in the affected libssh-based application if it is not required, or configure that application's libssh logging verbosity below SSH_LOG_PACKET (3). These measures address the GSSAPI logging path; they do not prevent other callers from passing zero-length input to the affected functions. Configuration and any required restart depend on the application using libssh. Changing the host's OpenSSH sshd_config or restarting the OpenSSH sshd service is not a general mitigation for applications using libssh. Apply the relevant vendor update containing the fix. Upstream fixed this issue in libssh 0.11.4 and 0.12.0; distribution packages may include a backported fix.
Source: CNA: redhatAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| Red Hat Enterprise Linux 10 Red Hat libssh
https://access.redhat.com/downloads/content/package-browser/ |
≥ 0:0.12.0-2.el10; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 9 Red Hat libssh
https://access.redhat.com/downloads/content/package-browser/ |
≥ 0:0.10.4-18.el9; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Hardened Images Red Hat libssh-main
https://catalog.redhat.com/software/containers/ |
≥ 0.12.0-1.1.hum1; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 6 Red Hat libssh2
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unaffected |
CNA: redhat |
| Red Hat Enterprise Linux 7 Red Hat libssh2
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unaffected |
CNA: redhat |
| Red Hat Enterprise Linux 8 Red Hat libssh
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat Hardened Images Red Hat libssh2
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unaffected |
CNA: redhat |
| Red Hat OpenShift Container Platform 4 Red Hat openshift/ose-rhel-coreos-8
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift Container Platform 4 Red Hat openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.0 / 6.5 medium |
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H | CNA: redhat |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://access.redhat.com/errata/RHSA-2026:18160CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:18683CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:7067CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-0966CNA: redhat · vdb-entry, x_refsource_REDHAT
- https://bugzilla.redhat.com/show_bug.cgi?id=2433121CNA: redhat · issue-tracking, x_refsource_REDHAT
- https://www.libssh.org/2026/02/10/libssh-0-12-0-and-0-11-4-security-releases/CNA: redhat
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