Bug 2523509 (CVE-2026-16599)

Summary:	CVE-2026-16599 wget: wget: Denial of Service via crafted FTP OPIE/S-KEY authentication challenge
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:	crizzo, gtanzill, jbuscemi, rhel-process-autobot, 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 wget's FTP OPIE/S-KEY authentication functionality. A malicious FTP server or a network attacker can send a specially crafted OPIE challenge. This challenge contains a sequence number that, when processed by wget, can lead to an excessive number of cryptographic computations. This prolonged computation can cause wget to become unresponsive, resulting in a denial of service.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2524564
Bug Blocks:

Description OSIDB Bzimport 2026-08-25 14:48:28 UTC

GNU wget is vulnerable to denial of service in its FTP OPIE/S-KEY authentication functionality. The server-supplied sequence number from the FTP challenge line is used as an iteration count for an MD5 key-derivation loop without any upper bound validation. A malicious FTP server or a network attacker positioned to intercept FTP traffic can send a crafted OPIE challenge with a sequence number near INT_MAX, causing wget to perform up to approximately 2.1 billion MD5 computations and suspend for some time. The --timeout option does not mitigate this because it applies only to network I/O, not CPU computation.


This issue was fixed in commit e9697d98e7249b0f68a6be040a4f3dcc5bc101fa