Bug 2555143 (CVE-2026-98793)

Summary:	CVE-2026-98793 kernel: netfilter: bpf: reject invalid NAT manipulation types
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:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, 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. Missing validation of Network Address Translation (NAT) manipulation types in BPF connection tracking helpers allows a local user with permissions to run BPF programs to trigger a system crash. By supplying an invalid manipulation type, an attacker can cause the kernel to access uninitialized data structures or trigger a kernel panic, resulting in a Denial of Service (DoS).	Story Points:	---
Clone Of:		Environment:
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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 2026-10-18 15:56:51 UTC

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

netfilter: bpf: reject invalid NAT manipulation types

As bpf_ct_set_nat_info() is not validating the NAT manipulation type a
wrong value can be passed directly to nf_nat_setup_info(). This triggers
the WARN_ON() at nf_nat_setup_info() and if panic_on_warn isn't set,
then IPS_SRC_NAT_DONE is set without adding nat_bysource and conntrack
cleanup tries to unlink an uninitialized hlist node.

Fix this by checking that NAT manipulation type is correct before
calling nf_nat_setup_info(). In addition, if the WARN_ON is hit, return
NF_DROP instead of continuing with the processing to avoid similar
situations in the future.

Comment 1 Mauro Matteo Cascella 2026-10-23 11:23:43 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98793.mbox