Bug 2521375 (CVE-2026-74669)

Summary:	CVE-2026-74669 kernel: ipvs: clear IPv4 options after rebasing tunnel ICMP errors
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability-draft	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	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 the Linux kernel's IP Virtual Server (IPVS) component. When processing Internet Control Message Protocol (ICMP) errors for tunneled packets, the system can incorrectly use a stale IPv4 option offset. A remote attacker could exploit this by sending a specially crafted ICMP packet, leading to a stack out-of-bounds write. This vulnerability could result in a denial of service or potentially arbitrary code execution.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-08-22 15:42:26 UTC

In the Linux kernel, the following vulnerability has been resolved:

ipvs: clear IPv4 options after rebasing tunnel ICMP errors

ip_vs_in_icmp() rebases an skb from the outer ICMP packet to the
quoted original request before passing it to icmp_send(). However,
IPCB(skb)->opt still describes the outer IPv4 header.

A timestamp option in the outer header can therefore leave an offset
that points into the quoted transport header after the rebase.
__ip_options_echo() treats a byte at that stale location as the option
length and copies it into the fixed-size option storage on the
__icmp_send() stack, causing a stack out-of-bounds write.

Clear the stale option metadata after resetting the network header.
Keep the remaining control block fields, including the ingress
interface used by the ICMP response path.

Comment 1 gkamathe 2026-08-24 09:01:58 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026082229-CVE-2026-74669-f574@gregkh/T