Libssh: libssh: denial of service via zero-length input in ssh_get_hexa()
Priority MEDIUM 43CWE-124Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · High
- Fix status
- Partial Red Hat: 5 fixed, 2 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00604 49th percentileScored 2026-11-07
Fix Partial Red Hat: 3 advisoriesRed Hat: 5 fixed, 2 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | — | 0.12.0-2.el10 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 9 | — | 0.10.4-18.el9 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 9 | — | 0.10.4-18.el9 | Patch available | CNA |
| Red Hat | Red Hat Hardened Images | — | 0.12.0-1.1.hum1 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 6 | — | — | Not affected | CNA |
| Red Hat | Red Hat Enterprise Linux 7 | — | — | Not affected | CNA |
| Red Hat | Red Hat Enterprise Linux 8 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Hardened Images | — | — | Not affected | CNA |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — | No fix listed | CNA |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — | No fix listed | CNA |
- Red Hat Enterprise Linux 10 VendorRed Hat Affected — Fixed in 0.12.0-2.el10 Patch available CNA
- Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in 0.10.4-18.el9 Patch available CNA
- Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in 0.10.4-18.el9 Patch available CNA
- Red Hat Hardened Images VendorRed Hat Affected — Fixed in 0.12.0-1.1.hum1 Patch available CNA
- Red Hat Enterprise Linux 6 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat Enterprise Linux 7 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat Enterprise Linux 8 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Hardened Images VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — No fix listed CNA
CPE configurations NVD · 6
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:libssh:libssh:*:*:*:*:*:*:*:* | before 0.11.4 | Vulnerable | libssh |
| cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | Red Hat |
| cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:* | 4.0 | Vulnerable | Red Hat |
| cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* | 8.0 | Vulnerable | Red Hat |
| cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Red Hat |
| cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Red Hat |
- cpe:2.3:a:libssh:libssh:*:*:*:*:*:*:*:* Versions before 0.11.4 Vulnerable ·libssh
- cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Red Hat
- cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:* Versions 4.0 Vulnerable ·Red Hat
- cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* Versions 8.0 Vulnerable ·Red Hat
- cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Red Hat
- cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Red Hat
Remediation
Red Hat 3 advisories
- RHSA-2026:18683 Released 2026-05-19 · Red Hat rating Moderatelibssh security update
- Red Hat Enterprise Linux AppStream (v. 9) libssh-devel-0.10.4-18.el9
- Red Hat Enterprise Linux BaseOS (v. 9) libssh-0.10.4-18.el9, libssh-config-0.10.4-18.el9
- RHSA-2026:18160 Released 2026-05-19 · Red Hat rating Moderatelibssh security update
- Red Hat Enterprise Linux AppStream (v. 10) libssh-devel-0.12.0-2.el10
- Red Hat Enterprise Linux BaseOS (v. 10) libssh-0.12.0-2.el10, libssh-config-0.12.0-2.el10
- RHSA-2026:7067 Released 2026-04-08 · Red Hat rating ModerateRed Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images libssh-0.12.0-1.1.hum1@aarch64, libssh-0.12.0-1.1.hum1@src, libssh-0.12.0-1.1.hum1@x86_64 +4
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6 and 5 more products — RHSA-2026:18160
5 records Highest priority Priority MEDIUM 1 MEDIUM, 4 LOW
Other records, highest priority first
- TI-2026-00730 Libssh: improper sanitation of paths received from scp serversPriority LOW 28
- TI-2026-00733 Libssh: libssh: denial of service via inefficient regular expression processingPriority LOW 24
- TI-2026-00734 Libssh: libssh: denial of service due to malformed sftp messagePriority LOW 16
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AppStream (v. 10) | Fixed | RHSA-2026:18160 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2026:18683 |
| Red Hat Enterprise Linux BaseOS (v. 10) | Fixed | RHSA-2026:18160 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2026:18683 |
| Red Hat Hardened Images | Fixed | RHSA-2026:7067 |
Not affected: 3 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Hardened Images
Timeline
- 2026-10-02 Threatist record created from CVE-2026-0966
- 2026-10-03 Alias added: GHSA-wcqf-w94x-4wg2
References
More Red Hat Enterprise Linux vulnerabilities
- TI-2019-08259 Underflow in PHP-FPM can lead to RCE KEVCVSS 3.1CRITICAL 9.8
- TI-2018-10530 Code injection in [UNKNOWN] RichFaces KEVCVSS 3.1CRITICAL 9.8
- TI-2014-05975 GNU Bash through 4.3 bash43-025 processes trailing strings after certain malformed… KEVCVSS 3.1CRITICAL 9.8
- TI-2014-05157 GNU Bash through 4.3 processes trailing strings after function definitions in the values… KEVCVSS 3.1CRITICAL 9.8
- TI-2025-23530 Sudo before 1.9.17p1 allows local users to obtain root access because /etc/nsswitch.conf… KEVCVSS 3.1CRITICAL 9.3
- TI-2021-17490 mod_proxy SSRF KEVCVSS 3.1CRITICAL 9.0
Sources
- CVE-2026-0966 · CVE Program
- CVE-2026-0966 · NVD
- FIRST EPSS
- GHSA-wcqf-w94x-4wg2 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-0966 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences