CVE-2026-59851
published 2026-07-21CVE-2026-59851: A flaw was found in libssh. On servers with GSSAPIKeyExchange enabled, the gssapi-keyex path does not verify whether the authenticated Kerberos principal is…
PriorityP354high8.8CVSS 3.1
AVNACLPRLUINSUCHIHAH
EPSS
0.49%
41.2th percentile
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
2 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| libssh | libssh | — | — |
| redhat | enterprise_linux | — | — |
CVSS provenance
nvdv3.18.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_redhat8.8HIGH
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Red Hat
libssh: libssh: authentication bypass via missing GSSAPI principal check
vendor_redhat·2026-07-21·CVSS 8.8
CVE-2026-59851 [HIGH] CWE-863 libssh: libssh: authentication bypass via missing GSSAPI principal check
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.
Mitigation: Disable GSSAPIKeyExchange.
Package: libssh (Red Hat Enterprise Linux 10) - Affected
Package: libssh (Red Hat Enterprise Linux 8) - Not affected
Package: libssh (Red Hat Enterprise Linux 9) - Not affected
Package: libssh (Red Hat Hardened Images) - Affected
VulDB
Red Hat Enterprise Linux GSSAPI improper authorization (Nessus ID 337346)
vuldb·2026-08-18·CVSS 8.8
CVE-2026-59851 [HIGH] Red Hat Enterprise Linux GSSAPI improper authorization (Nessus ID 337346)
A vulnerability labeled as very critical has been found in Red Hat Enterprise Linux. The affected element is an unknown function of the component GSSAPI. Such manipulation leads to improper authorization.
This vulnerability is documented as CVE-2026-59851. The attack can be executed remotely. There is not any exploit available.
GHSA
A flaw was found in libssh.
ghsa_unreviewed·2026-07-21
CVE-2026-59851 [HIGH] CWE-863 A flaw was found in libssh.
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.
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-59851 libssh: libssh: authentication bypass via missing GSSAPI principal check [fedora-all]
bugzilla·2026-07-21·CVSS 8.8
CVE-2026-59851 [HIGH] CVE-2026-59851 libssh: libssh: authentication bypass via missing GSSAPI principal check [fedora-all]
CVE-2026-59851 libssh: libssh: authentication bypass via missing GSSAPI principal check [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
A flaw was found in libssh server-side GSSAPIKeyExchange authorization. In ssh_packet_userauth_request() in src/messages.c, the gssapi-keyex login path granted success after Kerberos authentication without dispatching the callback that verifies whether the authenticated principal is authorized for the requested local user. On servers with GSSAPIKeyExchange enabled, an authenticated client can therefore log in as an arbitrary local user if the missing principal-to-user
Bugzilla
CVE-2026-59851 libssh: libssh: authentication bypass via missing GSSAPI principal check
bugzilla·2026-07-08·CVSS 8.8
CVE-2026-59851 [HIGH] CVE-2026-59851 libssh: libssh: authentication bypass via missing GSSAPI principal check
CVE-2026-59851 libssh: libssh: authentication bypass via missing GSSAPI principal check
A flaw was found in libssh server-side GSSAPIKeyExchange authorization. In ssh_packet_userauth_request() in src/messages.c, the gssapi-keyex login path granted success after Kerberos authentication without dispatching the callback that verifies whether the authenticated principal is authorized for the requested local user. On servers with GSSAPIKeyExchange enabled, an authenticated client can therefore log in as an arbitrary local user if the missing principal-to-user authorization check is relied upon for access control.
2026-07-21
Published