Bug 2503674 - CVE-2026-59849 libssh: libssh: denial of service via automatic certificate authentication loop [fedora-all]
Summary: CVE-2026-59849 libssh: libssh: denial of service via automatic certificate au...
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Fedora
Classification: Fedora
Component: libssh
Version: rawhide
Hardware: Unspecified
OS: Unspecified
low
low
Target Milestone: ---
Assignee: Andreas Schneider
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard: {"flaws": ["87e800dc-fbf1-44ec-bad5-5...
Depends On:
Blocks: CVE-2026-59849
TreeView+ depends on / blocked
 
Reported: 2026-07-21 15:15 UTC by Vladimir Vasilev
Modified: 2026-07-23 01:20 UTC (History)
5 users (show)

Fixed In Version: libssh-0.11.5-1.fc43 libssh-0.12.1-1.fc44
Clone Of:
Environment:
Last Closed: 2026-07-23 01:03:36 UTC
Type: ---
Embargoed:
fedora-admin-xmlrpc: mirror+


Attachments (Terms of Use)

Description Vladimir Vasilev 2026-07-21 15:15:19 UTC
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 automatic certificate-based public key authentication. In ssh_userauth_publickey_auto() in src/auth.c, the iterator over certificate candidates was not advanced correctly when configured certificates were missing or repeatedly rejected by the server. Under specific non-default certificate configurations, this could cause the client to restart the same authentication attempts indefinitely, leading to denial of service.

Comment 1 Fedora Update System 2026-07-22 09:32:52 UTC
FEDORA-2026-0e46c91ccf (libssh-0.12.1-1.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-0e46c91ccf

Comment 2 Fedora Update System 2026-07-22 09:33:50 UTC
FEDORA-2026-063caa9112 (libssh-0.11.5-1.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-063caa9112

Comment 3 Fedora Update System 2026-07-23 01:03:36 UTC
FEDORA-2026-063caa9112 (libssh-0.11.5-1.fc43) has been pushed to the Fedora 43 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 4 Fedora Update System 2026-07-23 01:20:29 UTC
FEDORA-2026-0e46c91ccf (libssh-0.12.1-1.fc44) has been pushed to the Fedora 44 stable repository.
If problem still persists, please make note of it in this bug report.


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