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Fencer Intel
high 8.8

CVE-2026-59851 json

Libssh: libssh: authentication bypass via missing gssapi principal check

published 3mo ago modified 6d ago also EUVD-2026-46268

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

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.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 10 0:0.12.0-3.el10_2
  • Red Hat Red Hat Hardened Images 0.12.1-4.hum1
  • libssh Debian 14 0.12.1-1

debian advisories DEBIAN-CVE-2026-59851

  • libssh RHEL 10.2 0.12.0-3.el10_2
  • libssh-config RHEL 10.2 0.12.0-3.el10_2
  • libssh hummingbird 1 0.12.1-4.hum1
  • libssh-config hummingbird 1 0.12.1-4.hum1

red hat advisories RHSA-2026:55855RHSA-2026:42922

  • libssh AlmaLinux 10 0.12.0-3.el10_2
  • libssh-config AlmaLinux 10 0.12.0-3.el10_2

almalinux advisories ALSA-2026:55855

  • libssh Rocky Linux 10 0.12.0-3.el10_2

rocky linux advisories RLSA-2026:55855

  • libssh Alpine 3.24 0.12.1-r0

alpine advisories ALPINE-CVE-2026-59851

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2026-59851 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-59851 updated cvss 8.8

libssh: libssh: authentication bypass via missing GSSAPI principal check

  • Red Hat Enterprise Linux AppStream (v. 10) libssh-devel 0.12.0-3.el10_2, libssh-debuginfo 0.12.0-3.el10_2, libssh-debugsource 0.12.0-3.el10_2 Red Hat Enterprise Linux BaseOS (v. 10) libssh 0.12.0-3.el10_2, libssh-config 0.12.0-3.el10_2
    fixed: vendor fix “Disable GSSAPIKeyExchange.” RHSA-2026:55855
  • Red Hat Hardened Images libssh 0.12.1-4.hum1, libssh-config 0.12.1-4.hum1
    fixed: vendor fix “Disable GSSAPIKeyExchange.” RHSA-2026:42922
  • Red Hat Enterprise Linux 8 libssh, libssh-config Red Hat Enterprise Linux 9 libssh, libssh-config
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
3mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Hardened Images
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.