Bug 2532283 (CVE-2026-80929)

Summary:	CVE-2026-80929 kernel: sysctl: move the "cad_pid" entry from pid_table[] to kern_reboot_table[]
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. A non-root user can exploit a vulnerability in the `sysctl` mechanism, specifically related to the `cad_pid` entry. By unsharing process ID (PID) and user namespaces, a local attacker can modify this global system control from a child namespace. This allows a user without administrative privileges to alter a critical system setting that should only be modifiable by the root user, leading to privilege escalation.	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 2026-09-11 22:07:15 UTC

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

sysctl: move the "cad_pid" entry from pid_table[] to kern_reboot_table[]

cad_pid is global, and kill_cad_pid() is only used in the root namespace.

However, due to pid_table_root_permissions(), a non-root user can unshare
pid/user namespaces and modify it from the child namespace. This makes no
sense and is simply wrong.

Move it to kern_reboot_table[] where it logically belongs; this ensures
that only GLOBAL_ROOT_UID can read/modify this sysctl.

Note that this patch doesn't preserve "#ifdef CONFIG_PROC_SYSCTL" around
the "cad_pid"; CONFIG_PROC_SYSCTL selects CONFIG_SYSCTL, so it is always
set when kern_reboot_table[] is compiled.

Comment 1 Keith Grant 2026-09-14 13:18:31 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80929.mbox