CVE-2026-59851
Libssh: libssh: authentication bypass via missing gssapi principal check
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What happened?
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.
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| libsshRed Hat | unaffected: 0:0.12.0-3.el10_2 to < * | See vendor advisory |
| libssh-mainRed Hat | unaffected: 0.12.1-4.hum1 to < * | See vendor advisory |
| libsshRed Hat | Default status: unaffected | See vendor advisory |
| libsshRed Hat | Default status: unaffected | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.