Bug 2536439 (CVE-2026-93134)

Summary:	CVE-2026-93134 kernel: printk: Fix possible console use-after-free
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. When the `printk` function handles legacy console printing, a specific scenario involving context handover can lead to a use-after-free vulnerability. This occurs because the system fails to verify if a memory area has been freed after a handover, potentially allowing an attacker to corrupt memory. This could result in a denial of service or, in more severe cases, arbitrary code execution.	Story Points:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-17 17:52:56 UTC

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

printk: Fix possible console use-after-free

When emitting a record via legacy printing, it is possible that a handover
to another legacy printing context occurs. When a context has performed a
handover, the console SRCU read lock is released and the pointer to the
console struct might now be invalid. Therefore, after calling
nbcon_legacy_emit_next_record() or console_emit_next_record(), it is
necessary to check if a handover occurred _before_ further @con usage.

Sashiko pointed out that console_flush_one_record() was not doing this.

In console_flush_one_record(), after emitting a record, move the further
usage of @con after the handover check.

Comment 1 gkamathe 2026-09-18 18:10:40 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93134.mbox