Bug 2536786 (CVE-2026-92515)

Summary:	CVE-2026-92515 kernel: bpf: Preserve unique-field state across nested structs
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
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 Berkeley Packet Filter (BPF) component. This vulnerability occurs because the `btf_find_struct_field()` function incorrectly initializes a fresh 'seen mask' during recursive descent, allowing duplicate fields in nested structures. A local attacker can exploit this by crafting a malicious BPF Type Format (BTF) to trigger a kernel warning (`WARN_ON_ONCE()`) before capability checks, leading to a denial of service.	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 2026-09-17 19:33:12 UTC

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

bpf: Preserve unique-field state across nested structs

btf_find_struct_field() initializes a fresh seen mask for every recursive
descent. Unique special fields in different levels of the same aggregate
therefore do not see one another. The duplicate fields can reach
btf_parse_fields(), where they trigger an invariant WARN_ON_ONCE(). A
crafted user BTF can consequently trigger the warning before map creation
checks capabilities.

Initialize the seen mask once in btf_find_field() and pass the same pointer
through struct, datasec, and nested-struct walks. This gives the entire field
traversal one shared uniqueness state.

Comment 1 gkamathe 2026-09-21 03:27:59 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-92515.mbox