Bug 2482140 (CVE-2026-46101)

Summary:	CVE-2026-46101 kernel: netfilter: reject zero shift in nft_bitwise
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
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's Netfilter subsystem. Specifically, the `nft_bitwise` expression incorrectly handles zero shift operands during initialization. This can lead to undefined behavior within the kernel, potentially causing system instability. An attacker could exploit this by crafting malformed Netfilter rules, preventing the system from processing network packets correctly.	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 2026-05-27 15:13:14 UTC

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

netfilter: reject zero shift in nft_bitwise

Reject zero shift operands for nft_bitwise left and right shift
expressions during initialization.

The carry propagation logic computes the carry from the adjacent 32-bit
word using BITS_PER_TYPE(u32) - shift. A zero shift operand turns this
into a 32-bit shift, which is undefined behaviour.

Reject zero shift operands in the control plane, alongside the existing
check for values greater than or equal to 32, so malformed rules never
reach the packet path.

Comment 1 Keith Grant 2026-05-27 16:39:50 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026052705-CVE-2026-46101-3102@gregkh/T