Bug 2498181 (CVE-2026-59848)

Summary:	CVE-2026-59848 libssh: libssh: denial of service via SFTP responses with unknown request IDs
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	rhel-process-autobot, security-response-team, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in libssh. A malicious SFTP server can send responses for unknown request IDs that libssh clients keep queued indefinitely, causing unbounded memory growth and client-side denial of service.	Story Points:	---
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Last Closed:		Type:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2503673
Bug Blocks:

Description OSIDB Bzimport 2026-07-08 18:22:48 UTC

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.