Description
A flaw was found in OpenSSH. This vulnerability, a heap out-of-bounds read, occurs during the cleanup of GSSAPI (Generic Security Service Application Programming Interface) indicators when a trailing NULL termination is missing in the auth-indicators array. A remote attacker, under specific configurations involving GSSAPI authentication and a Kerberos environment, could exploit this to cause the SSH authentication path to crash or abort. This leads to a denial of service (DoS), impacting the availability of the SSH service.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
| Red Hat | Red Hat Hardened Images | — | — |
| Red Hat | Red Hat Update Infrastructure 5 | — | — |
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Enterprise Linux 7 | — | — |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — |
| Red Hat | Red Hat OpenShift Container Platform 5 | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | openssh | 1:10.4p1-5 | — |
| Debian 14 | openssh-gssapi | No fix yet | — |
| Debian 13 | openssh | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | openssh-ssh1 | No fix yet | — |
| Ubuntu 26.04 LTS | openssh-ssh1 | No fix yet | — |
| Ubuntu 25.10 | openssh +1 | No fix yet | — |
| Ubuntu 24.04 LTS | openssh-ssh1 | No fix yet | — |
| Ubuntu 22.04 LTS | openssh-ssh1 | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | openssh-ssh1 | No fix yet | — |
| Ubuntu 18.04 LTS | openssh-ssh1 | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | openssh +5 | 9.9p1-25.el10_2 | RHSA-2026:47757 |
| RHEL 9 | openssh +4 | 9.9p1-9.el9_8 | RHSA-2026:47756 |
| RHEL 9 | pam_ssh_agent_auth | 0.10.4-7.9.el9_8 | RHSA-2026:47756 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Hardened Images 1 | openssh +6 | 10.3p1-6.hum1 | RHSA-2026:36759 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | openssh +5 | 9.9p1-25.el10_2.alma.1 | ALSA-2026:47757 |
| AlmaLinux 9 | openssh +4 | 9.9p1-9.el9_8.alma.1 | ALSA-2026:47756 |
| AlmaLinux 9 | pam_ssh_agent_auth | 0.10.4-7.9.el9_8.alma.1 | ALSA-2026:47756 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | openssh | 9.9p1-25.el10_2.rocky.0.1 | RLSA-2026:47757 |
| Rocky Linux 9 | openssh | 9.9p1-9.el9_8.rocky.0.1 | RLSA-2026:47756 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | openssh +5 | 9.9p1-25.0.1.el10_2 | ELSA-2026-47757 |
| Oracle Linux 9 | openssh +4 | 9.9p1-9.0.1.el9_8 | ELSA-2026-47756 |
| Oracle Linux 9 | pam_ssh_agent_auth | 0.10.4-7.9.0.1.el9_8 | ELSA-2026-47756 |
Advisories 10
- WID-SEC-2026-2039 OpenSSH: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2026
- ALSA-2026:47756 Important: openssh security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:47757 Important: openssh security update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2026:47757 Red Hat Security Advisory: openssh security update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2026:47756 Red Hat Security Advisory: openssh security update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2026:36759 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 15, 2026
- ELSA-2026-47756 Important: openssh security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Aug 6, 2026
- RLSA-2026:47756 Important: openssh security update Rocky Linux Security Advisories · Jul 30, 2026
- RLSA-2026:47757 Important: openssh security update Rocky Linux Security Advisories · Jul 30, 2026
- ELSA-2026-47757 Important: openssh security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Jul 30, 2026
References
- RHSA-2026:36759 vendor-advisory
- RHSA-2026:47756 vendor-advisory
- RHSA-2026:47757 vendor-advisory
- RHSA-2026:54387 vendor-advisory
- RHSA-2026:58981 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-55654 vdb-entry
- RHBZ#2462493 issue-tracking