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Fencer Vulns
medium 4.3

CVE-2026-59850 json

Libssh: libssh: use-after-free via data callbacks on closed channels

published 2026-07-21 3 mo ago modified 2026-09-01 2 mo ago also EUVD-2026-46266

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 28%
public exploits
0
none known

Summary

A flaw was found in libssh. If data packets are processed after a channel is closed, channel data callbacks can be invoked after the associated data has already been freed, leading to crashes or possible use-after-free conditions.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 10 0:0.12.0-3.el10_2
  • Red Hat Red Hat Enterprise Linux 8 0:0.9.6-17.el8_10
  • Red Hat Red Hat Enterprise Linux 9 0:0.10.4-19.el9_8
  • Red Hat Red Hat Hardened Images 0.12.1-4.hum1
  • libssh Debian 12 0.10.6-0+deb12u3
  • libssh Debian 13 0.11.5-0+deb13u1
  • libssh Debian 14 0.12.1-1

debian advisories DEBIAN-CVE-2026-59850

  • libssh Ubuntu 22.04 LTS 0.9.6-2ubuntu0.22.04.8
  • libssh Ubuntu 24.04 LTS 0.10.6-2ubuntu0.5
  • libssh Ubuntu 26.04 LTS 0.11.3-1ubuntu2.1

ubuntu advisories UBUNTU-CVE-2026-59850

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libssh RHEL 9 0.10.4-19.el9_8
  • libssh-config RHEL 9 0.10.4-19.el9_8
  • libssh RHEL 8 0.9.6-17.el8_10
  • libssh-config RHEL 8 0.9.6-17.el8_10
  • 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-2026:62217RHSA-2026:62218RHSA-2026:55855RHSA-2026:42922

  • libssh Linux Micro 6.1 0.10.6-slfo.1.1_6.1
  • libssh Linux Micro 6.0 0.10.6-5.1
  • libssh SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +8 more 0.9.8-150400.3.20.1
  • libssh SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Basesystem 15 SP7 0.9.8-150600.11.15.1
  • libssh SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 0.11.5-160000.1.1
  • libssh SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 0.9.8-3.24.1

suse advisories SUSE-SU-2026:23168-1SUSE-SU-2026:23056-1SUSE-SU-2026:3463-1SUSE-SU-2026:3330-1SUSE-SU-2026:3302-1SUSE-SU-2026:22940-1

  • libssh openSUSE Tumbleweed 0.11.5-1.2
  • libssh openSUSE Leap 16.0 0.11.5-160000.1.1

opensuse advisories openSUSE-SU-2026:11377-1openSUSE-SU-2026:21444-1

  • libssh AlmaLinux 9 0.10.4-19.el9_8
  • libssh-config AlmaLinux 9 0.10.4-19.el9_8
  • libssh AlmaLinux 8 0.9.6-17.el8_10
  • libssh-config AlmaLinux 8 0.9.6-17.el8_10
  • libssh AlmaLinux 10 0.12.0-3.el10_2
  • libssh-config AlmaLinux 10 0.12.0-3.el10_2

almalinux advisories ALSA-2026:62217ALSA-2026:62218ALSA-2026:55855

  • libssh Rocky Linux 9 0.10.4-19.el9_8
  • libssh Rocky Linux 8 0.9.6-17.el8_10
  • libssh Rocky Linux 10 0.12.0-3.el10_2

rocky linux advisories RLSA-2026:62217RLSA-2026:62218RLSA-2026:55855

  • libssh Alpine 3.24 0.12.1-r0

alpine advisories ALPINE-CVE-2026-59850

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

  • libssh Azure Linux 3.0 0.10.6-9

azure linux advisories AZL-93258

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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-2026-59850 updated cvss 4.3

libssh: libssh: use-after-free via data callbacks on closed channels

  • Red Hat Enterprise Linux AppStream (v. 8) libssh-devel 0.9.6-17.el8_10, libssh-debuginfo 0.9.6-17.el8_10, libssh-debugsource 0.9.6-17.el8_10
    fixed: vendor fix “Manually verify the channel is not closed inside your channel data callbacks.” RHSA-2026:62218
  • Red Hat Enterprise Linux AppStream (v. 9) libssh-devel 0.10.4-19.el9_8, libssh-debuginfo 0.10.4-19.el9_8, libssh-debugsource 0.10.4-19.el9_8
    fixed: vendor fix “Manually verify the channel is not closed inside your channel data callbacks.” RHSA-2026:62217
  • 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
    fixed: vendor fix “Manually verify the channel is not closed inside your channel data callbacks.” RHSA-2026:55855
  • Red Hat Enterprise Linux BaseOS (v. 8) libssh 0.9.6-17.el8_10, libssh-config 0.9.6-17.el8_10
    fixed: vendor fix “Manually verify the channel is not closed inside your channel data callbacks.” RHSA-2026:62218
  • Red Hat Enterprise Linux BaseOS (v. 9) libssh 0.10.4-19.el9_8, libssh-config 0.10.4-19.el9_8
    fixed: vendor fix “Manually verify the channel is not closed inside your channel data callbacks.” RHSA-2026:62217
  • 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 “Manually verify the channel is not closed inside your channel data callbacks.” RHSA-2026:55855
  • Red Hat Hardened Images libssh 0.12.1-4.hum1, libssh-config 0.12.1-4.hum1
    fixed: vendor fix “Manually verify the channel is not closed inside your channel data callbacks.” RHSA-2026:42922

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
partial
Assessed
3 mo ago

Exploit prediction

0.35% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

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

Classification

Weakness

References

Sources

Fencer Vulns 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.