CVE-2026-59998
Description
A flaw was found in OpenSSH. The sshd component has an undocumented security-relevant behavior where GSSAPIStrictAcceptorCheck has no value when the server is in a Windows Active Directory environment. This could lead to unintended information disclosure and impact data integrity.
Mitigation
To mitigate this issue, avoid using GSSAPI authentication for `sshd` when the server is integrated with a Windows Active Directory environment. If GSSAPI authentication is not strictly required, it can be disabled by setting `GSSAPIAuthentication no` in the `/etc/ssh/sshd_config` file. After modifying the configuration, the `sshd` service must be restarted for the changes to take effect. Note that restarting the `sshd` service will terminate all active SSH sessions.
bashAlternatively, if GSSAPI authentication is necessary in such an environment, ensure that the network path between the client and the `sshd` server, and to the Active Directory, is secured and trusted to prevent man-in-the-middle attacks.
# echo "GSSAPIAuthentication no" >> /etc/ssh/sshd_config
# systemctl restart sshd
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | 6.5 | 4.8 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | High |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | Low | Low | Low |
| Integrity Impact | Low | Low | Low |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory; Read Application Data
When reusing a resource such as memory or a program variable, the original contents of that resource may not be cleared before it is sent to an untrusted party.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
The uninitialized resource may contain values that cause program flow to change in ways that the programmer did not intend.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
