CVE-2026-59851Network attack vector

Authenticated arbitrary-user login via skipped authorization callback

Published Jul 21, 2026 · Updated Jul 21, 2026

Incorrect authorization in Red Hat libssh packages allows remote authenticated users to log in as arbitrary local users over SSH. The gssapi-keyex branch of ssh_packet_userauth_request() in src/messages.c returns authentication success without invoking the principal-to-user authorization callback. Exploitation requires GSSAPIKeyExchange and valid Kerberos authentication, after which the client obtains the requested local account's SSH access.

CVSS severity8.8
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Incorrect authorization in Red Hat libssh packages allows remote authenticated users to log in as arbitrary local users over SSH. The gssapi-keyex branch of ssh_packet_userauth_request() in src/messages.c returns authentication success without invoking the principal-to-user authorization callback. Exploitation requires GSSAPIKeyExchange and valid Kerberos authentication, after which the client obtains the requested local account's SSH access.

The record

CVE
CVE-2026-59851
Published
Jul 21, 2026
Updated
Jul 21, 2026
Vendor
389 Directory Server
Product
Red Hat Enterprise Linux 10
Classifications
CWE-863, T1078
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

389 Directory Server · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
389 Directory Server · Red Hat Hardened ImagesAffected versions are unavailable in this record.

Published CVSS scores

8.8Red HatCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1078Valid Accounts

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo