CVE-2026-3497
Description
A flaw was found in the OpenSSH GSSAPI (Generic Security Service Application Program Interface) delta patches, as included in various Linux distributions. A remote attacker could exploit this by sending an unexpected GSSAPI message type during the key exchange process. This occurs because the sshpkt_disconnect() function, when called on an error, does not properly terminate the process, leading to the continued execution of the program with uninitialized connection variables. Accessing these uninitialized variables can lead to undefined behavior, potentially resulting in information disclosure or a denial of service.
Statement
IMPORTANT: This vulnerability affects the OpenSSH GSSAPI delta as implemented in Red Hat Enterprise Linux and OpenShift Container Platform. An unauthenticated attacker could send a specially crafted GSSAPI message during key exchange, leading to the use of uninitialized variables and potentially undefined behavior. The severity of the impact is dependent on compiler hardening configurations.
Mitigation
To mitigate this issue, disable GSSAPI key exchange in the OpenSSH server configuration. This prevents the server from processing GSSAPI messages, eliminating the vulnerability's attack surface.
Edit `/etc/ssh/sshd_config` and add or modify the line:
GSSAPIKeyExchange no
After saving the changes, restart the `sshd` service for the mitigation to take effect. This action will prevent users from authenticating via GSSAPI.
# 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 | 8.2 | 7.5 | 8.2 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | Low | None | Low |
| Integrity Impact | None | None | None |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
If the uninitialized pointer is used in a read operation, an attacker might be able to read sensitive portions of memory.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the uninitialized pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the uninitialized pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
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