Bug 2503673

Summary: CVE-2026-59848 libssh: libssh: denial of service via SFTP responses with unknown request IDs [fedora-all]
Product: [Fedora] Fedora Reporter: Vladimir Vasilev <vvasilev>
Component: libsshAssignee: Andreas Schneider <asn>
Status: CLOSED ERRATA QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: medium    
Version: rawhideCC: ansasaki, asn, jjelen, negativo17, shebburn
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---Flags: fedora-admin-xmlrpc: mirror+
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["45084a98-a255-4c96-bf32-ce3de88b55ab"]}
Fixed In Version: libssh-0.11.5-1.fc43 libssh-0.12.1-1.fc44 Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2026-07-23 01:03:32 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2498181    

Description Vladimir Vasilev 2026-07-21 15:13:35 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 client-side SFTP message handling. In sftp_get_message() in src/sftp_common.c, SFTP responses carrying unknown request IDs were accepted and kept queued instead of being rejected. A malicious SFTP server can repeatedly send responses for request IDs that were never issued by the client, causing unbounded growth of queued messages and leading to client-side memory exhaustion and denial of service.
Comment 1 Fedora Update System 2026-07-22 09:32:49 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 09:33:47 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 01:03:32 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 01:20:26 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.