RHSA-2026:55855HighCVSS 8.8

Red Hat Security Advisory: libssh security update

Published
August 17, 2026
Last Modified
August 17, 2026

🔗 CVE IDs covered (11)

CVE-2026-59845 →CVE-2026-59847 →CVE-2026-59848 →CVE-2026-59851 →CVE-2026-59843 →CVE-2026-59846 →CVE-2026-59849 →CVE-2026-59850 →CVE-2026-15370 →CVE-2026-59842 →CVE-2026-59844 →

📋 Description

CVE-2026-15370 — libssh: libssh: stack buffer overflow in SFTP server longname construction CVE-2026-59842 — libssh: libssh: information disclosure via short GSSAPI Curve25519 public key CVE-2026-59843 — libssh: libssh: denial of service via zero advertised channel packet size CVE-2026-59844 — libssh: libssh: denial of service via oversized SFTP read length CVE-2026-59845 — libssh: libssh: denial of service via unchecked ProxyCommand fork() failure CVE-2026-59846 — libssh: libssh: information disclosure via ProxyCommand %r username expansion CVE-2026-59847 — libssh: libssh: integrity downgrade via OpenSSL AES-GCM tag verification CVE-2026-59848 — libssh: libssh: denial of service via SFTP responses with unknown request IDs CVE-2026-59849 — libssh: libssh: denial of service via automatic certificate authentication loop CVE-2026-59850 — libssh: libssh: use-after-free via data callbacks on closed channels CVE-2026-59851 — libssh: libssh: authentication bypass via missing GSSAPI principal check

🎯 Affected products28

  • Red Hat Enterprise Linux AppStream (v. 10)
  • Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-0:0.12.0-3.el10_2.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-0:0.12.0-3.el10_2.ppc64le as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-0:0.12.0-3.el10_2.s390x as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-0:0.12.0-3.el10_2.src as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-0:0.12.0-3.el10_2.x86_64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-config-0:0.12.0-3.el10_2.noarch as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-debuginfo-0:0.12.0-3.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libssh-debuginfo-0:0.12.0-3.el10_2.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-debuginfo-0:0.12.0-3.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libssh-debuginfo-0:0.12.0-3.el10_2.ppc64le as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-debuginfo-0:0.12.0-3.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libssh-debuginfo-0:0.12.0-3.el10_2.s390x as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-debuginfo-0:0.12.0-3.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libssh-debuginfo-0:0.12.0-3.el10_2.x86_64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-debugsource-0:0.12.0-3.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libssh-debugsource-0:0.12.0-3.el10_2.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-debugsource-0:0.12.0-3.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libssh-debugsource-0:0.12.0-3.el10_2.ppc64le as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-debugsource-0:0.12.0-3.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libssh-debugsource-0:0.12.0-3.el10_2.s390x as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-debugsource-0:0.12.0-3.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libssh-debugsource-0:0.12.0-3.el10_2.x86_64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libssh-devel-0:0.12.0-3.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libssh-devel-0:0.12.0-3.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libssh-devel-0:0.12.0-3.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libssh-devel-0:0.12.0-3.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10)

✅ Remediation

For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Workaround: No workaround available. Workaround: Disable GSSAPIKeyExchange or remove gss-curve25519-sha256- from GSSAPIKexAlgorithms if appropriate. Workaround: To mitigate this issue, avoid using the ProxyCommand feature in libssh client configurations. This prevents the vulnerable code path from being exercised, thereby eliminating the risk of local denial of service due to unchecked fork() failures. Workaround: Make sure you are not executing connections with untrusted username inputs. Workaround: Disable the [email protected] and [email protected] ciphers. Workaround: Do not connect to untrusted SFTP servers. Workaround: Do not connect to untrusted SSH servers and do not use certificates until patched. Workaround: Manually verify the channel is not closed inside your channel data callbacks. Workaround: Disable GSSAPIKeyExchange.

🔗 References (14)