libssh GSSAPIKeyEx Auth Bypass
CVE-2026-59851 Published on July 21, 2026
Libssh: libssh: authentication bypass via missing gssapi principal check
A flaw was found in libssh. On servers with GSSAPIKeyExchange enabled, the gssapi-keyex path does not verify whether the authenticated Kerberos principal is authorized for the requested local user, allowing authenticated clients to log in as arbitrary users.
Vulnerability Analysis
CVE-2026-59851 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Timeline
Reported to Red Hat.
Made public. 83 days later.
Weakness Type
What is an AuthZ Vulnerability?
The software performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.
CVE-2026-59851 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2026-59851
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