Bug 2536308 (CVE-2026-90210)

Summary:	CVE-2026-90210 kernel: bpf: Fix UAF in bpf_trampoline_multi_attach_free on update failure
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
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 Berkeley Packet Filter (BPF) component. This use-after-free (UAF) vulnerability occurs when the `bpf_trampoline_update()` function fails during an update operation. This failure can lead to a previously freed memory region being accessed, potentially resulting in system instability, denial of service, or the execution of arbitrary code.	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 17:18:10 UTC

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

bpf: Fix UAF in bpf_trampoline_multi_attach_free on update failure

When bpf_trampoline_update() fails before modify_fentry_multi()/
unregister_fentry_multi() is called, cur_image is unchanged
(cur_image == old_image) and ftrace still calls into it.  Freeing
old_image in that case causes a UAF.

Only free old_image when it differs from cur_image.

Comment 1 Mauro Matteo Cascella 2026-09-24 11:52:37 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90210.mbox