Vulnerability · Published Jun 23, 2026 · Assigned by redhat
CVE-2026-55654Openssh: heap out-of-bounds read in red hat enterprise linux versions of openssh gssapi indicator cleanup due to missing null sentinel termination
Low 3.7
In plain English
A low-severity out-of-bounds read 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 0.7% (higher than 51% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | openssh | 9.9p1-25.el10_2.alma.1 | ALSA-2026:47757 |
| AlmaLinux:9 | openssh | 9.9p1-9.el9_8.alma.1 | ALSA-2026:47756 |
| AlmaLinux:10 | openssh-askpass | 9.9p1-25.el10_2.alma.1 | ALSA-2026:47757 |
| AlmaLinux:9 | openssh-askpass | 9.9p1-9.el9_8.alma.1 | ALSA-2026:47756 |
| AlmaLinux:10 | openssh-clients | 9.9p1-25.el10_2.alma.1 | ALSA-2026:47757 |
| AlmaLinux:9 | openssh-clients | 9.9p1-9.el9_8.alma.1 | ALSA-2026:47756 |
| AlmaLinux:10 | openssh-keycat | 9.9p1-25.el10_2.alma.1 | ALSA-2026:47757 |
| AlmaLinux:9 | openssh-keycat | 9.9p1-9.el9_8.alma.1 | ALSA-2026:47756 |
| AlmaLinux:10 | openssh-keysign | 9.9p1-25.el10_2.alma.1 | ALSA-2026:47757 |
| AlmaLinux:10 | openssh-server | 9.9p1-25.el10_2.alma.1 | ALSA-2026:47757 |
| AlmaLinux:9 | openssh-server | 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 |
| Debian:13 | openssh | no fix listed | DEBIAN-CVE-2026-55654 |
| Debian:14 | openssh | 1:10.4p1-5 | DEBIAN-CVE-2026-55654 |
| Debian:14 | openssh-gssapi | no fix listed | DEBIAN-CVE-2026-55654 |
| Rocky Linux:10 | openssh | 0:9.9p1-25.el10_2.rocky.0.1 | RLSA-2026:47757 |
| Rocky Linux:9 | openssh | 0:9.9p1-9.el9_8.rocky.0.1 | RLSA-2026:47756 |
| Ubuntu:25.10 | openssh | no fix listed | UBUNTU-CVE-2026-55654 |
| Ubuntu:22.04:LTS | openssh-ssh1 | no fix listed | UBUNTU-CVE-2026-55654 |
| Ubuntu:24.04:LTS | openssh-ssh1 | no fix listed | UBUNTU-CVE-2026-55654 |
| Ubuntu:25.10 | openssh-ssh1 | no fix listed | UBUNTU-CVE-2026-55654 |
| Ubuntu:26.04:LTS | openssh-ssh1 | no fix listed | UBUNTU-CVE-2026-55654 |
| Ubuntu:26.10 | openssh-ssh1 | no fix listed | UBUNTU-CVE-2026-55654 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
| Red Hat | Red Hat Hardened Images | see references |
| Red Hat | Red Hat Update Infrastructure 5 | see references |
| Red Hat | Red Hat Update Infrastructure 5 | see references |
| Red Hat | Red Hat Update Infrastructure 5 | see references |
| Red Hat | Red Hat Update Infrastructure 5 | see references |
| Red Hat | Red Hat Enterprise Linux 6 | see references |
| Red Hat | Red Hat Enterprise Linux 7 | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4 | see references |
Weakness: CWE-125 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
References
- RHSA-2026:36759 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:47756 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:47757 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:54387 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:58981 vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-55654 vdb-entry, x_refsource_REDHAT
- RHBZ#2462493 issue-tracking, x_refsource_REDHAT