Bug 2536675 (CVE-2026-90146)

Summary:	CVE-2026-90146 kernel: bpf, xdp: move offload check into dev_xdp_install()
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. The `bpf_xdp_link_update()` function bypasses necessary checks when updating an eXpress Data Path (XDP) program. A local user can first create an XDP link with a standard program and then use `BPF_LINK_UPDATE` to replace it with an offloaded or device-bound program. This circumvents the intended offload checks, causing the program to run on the software path instead of being properly offloaded, which could lead to unexpected behavior or resource consumption.	Story Points:	---
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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 2026-09-17 19:04:13 UTC

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

bpf, xdp: move offload check into dev_xdp_install()

bpf_xdp_link_update() calls dev_xdp_install() directly and skips
dev_xdp_attach(), so the checks in dev_xdp_attach() do not run. A user can
make an XDP link with a normal program and then swap in an offloaded or
device-bound program with BPF_LINK_UPDATE, which puts it on the software
path.

dev_xdp_install() is the one place all three paths go through:
"ip link set xdp" and BPF_LINK_CREATE reach it via dev_xdp_attach(), and
BPF_LINK_UPDATE calls it directly. So move the program checks (offloaded,
bound to another device, device-bound in generic mode, native vs generic,
DEVMAP and CPUMAP) there, and keep only the netlink-flag check
(XDP_FLAGS_UPDATE_IF_NOEXIST) in dev_xdp_attach().

Comment 1 Keith Grant 2026-09-23 16:53:35 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90146.mbox