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.

Published: 2026-03-26 Last update: 2026-05-19 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-0966 is rated Moderate Risk (40.4/100): CVSS High severity, with low exploitation likelihood (EPSS 0.07%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-0966

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-21 0.17% 0.07% -0.10%
2 2026-04-20 0.09% 0.17% +0.09%
3 2026-03-27 — 0.09% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-0966

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.2 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 4.2 [email protected]
6.5 3.0 MEDIUM
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 4.2 [email protected]

Weakness enumeration for CVE-2026-0966

GitHub Security Advisory for CVE-2026-0966

GHSA-wcqf-w94x-4wg2 · Severity: medium — The API function `ssh_get_hexa()` is vulnerable, when 0-lenght input is provided to this function...

OS Trackers for CVE-2026-0966

vendor priority summary link
alpine — CVE-2026-0966: 1 source package rows (libssh); 2 state rows across 2 repos (3.23-community, edge-community); fixed 2, open 0. https://security.alpinelinux.org/vuln/CVE-2026-0966
debian not yet assigned CVE-2026-0966 not yet assigned priority: Debian including 1 source packages (libssh), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-0966
redhat medium — https://access.redhat.com/security/cve/CVE-2026-0966
suse medium CVE-2026-0966 severity moderate: SUSE including 276 source package names (1.1.1-1.40:libssh-config-0.9.8-150600.11.9.1, 1.1.1-1.40:libssh4-0.9.8-150600.11.9.1, …), 428 product×package rows across 85 product lines (Container private-registry/harbor-trivy-adapter, Container suse/ltss/sle12.5/sles12sp5, … (85 product lines)): Known Affected 231, Fixed 187, First Fixed 10. https://www.suse.com/security/cve/CVE-2026-0966/
ubuntu low CVE-2026-0966 low priority: Ubuntu including 1 source packages (libssh), 7 status rows across 7 suites (bionic, focal, jammy, noble, questing, upstream, xenial): released 7. https://ubuntu.com/security/CVE-2026-0966

Affected software / configurations for CVE-2026-0966

Vendor Product Version Raw CPE
libssh libssh < 0.11.4 cpe:2.3:a:libssh:libssh:*:*:*:*:*:*:*:*
redhat hardened_images — cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:*
redhat openshift_container_platform 4.0 cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
redhat enterprise_linux 10.0 cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*

References for CVE-2026-0966

cvelogic Threat Intelligence