Vulnerability · Published Jul 21, 2026 · Assigned by redhat
CVE-2026-59851Libssh: libssh: authentication bypass via missing gssapi principal check
High 8.8
In plain English
A high-severity incorrect authorization in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)8.8High
Exploit odds (30 days)0.5%top 57.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
A flaw was found in libssh. On servers with GSSAPIKeyExchange enabled, the gssapi-keyex path does not verify whether the authenticated Kerberos principal is authorized for the requested local user, allowing authenticated clients to log in as arbitrary users.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | libssh | 0.12.0-3.el10_2 | ALSA-2026:55855 |
| AlmaLinux:10 | libssh-config | 0.12.0-3.el10_2 | ALSA-2026:55855 |
| AlmaLinux:10 | libssh-devel | 0.12.0-3.el10_2 | ALSA-2026:55855 |
| Alpine:v3.24 | libssh | 0.12.1-r0 | ALPINE-CVE-2026-59851 |
| Debian:14 | libssh | 0.12.1-1 | DEBIAN-CVE-2026-59851 |
| Rocky Linux:10 | libssh | 0:0.12.0-3.el10_2 | RLSA-2026:55855 |
| Ubuntu:22.04:LTS | libssh | no fix listed | UBUNTU-CVE-2026-59851 |
| Ubuntu:24.04:LTS | libssh | no fix listed | UBUNTU-CVE-2026-59851 |
| Ubuntu:26.04:LTS | libssh | no fix listed | UBUNTU-CVE-2026-59851 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | see references |
| Red Hat | Red Hat Hardened Images | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
Weakness: CWE-863 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- RHSA-2026:42922 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:55855 vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-59851 vdb-entry, x_refsource_REDHAT
- RHBZ#2498184 issue-tracking, x_refsource_REDHAT