Bug 2516470 (CVE-2026-72350)

Summary:	CVE-2026-72350 kernel: netfilter: xt_u32: reject invalid shift counts
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	rhel-process-autobot, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
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Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's netfilter component, specifically in `xt_u32`. A local attacker with privileges to configure netfilter rules could craft a malicious `u32` rule with an invalid shift count. This could lead to an undefined shift out-of-bounds during packet evaluation, potentially causing a denial of service (DoS) or system instability.	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:

Description OSIDB Bzimport 2026-08-15 06:14:14 UTC

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

netfilter: xt_u32: reject invalid shift counts

u32_match_it() executes rule-supplied shift operands on a 32-bit
value. A malformed u32 rule can provide a shift count of 32 or more,
triggering an undefined shift out-of-bounds during packet evaluation.

Validate XT_U32_LEFTSH and XT_U32_RIGHTSH operands in
u32_mt_checkentry() and reject malformed rules before they reach the
packet path.

Comment 1 Keith Grant 2026-08-19 13:51:30 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081512-CVE-2026-72350-e1f8@gregkh/T