RCU violation via premature namespace reference release
Published Sep 25, 2026 · Updated Sep 25, 2026
Concurrency flaw in Linux 6.19 allows local users to trigger an RCU warning by racing namespace listing with mount-namespace teardown. The legitimize_ns() path takes a candidate reference before may_list_ns() checks visibility, so denial can release the final mount-namespace reference and let put_mnt_ns() sleep inside an RCU read-side critical section. An ordinary local user can reach the race by repeatedly calling listns() while creating and destroying mount namespaces; the demonstrated result is a kernel warning rather than a confirmed crash.
Summary
What happened
Concurrency flaw in Linux 6.19 allows local users to trigger an RCU warning by racing namespace listing with mount-namespace teardown. The legitimize_ns() path takes a candidate reference before may_list_ns() checks visibility, so denial can release the final mount-namespace reference and let put_mnt_ns() sleep inside an RCU read-side critical section. An ordinary local user can reach the race by repeatedly calling listns() while creating and destroying mount namespaces; the demonstrated result is a kernel warning rather than a confirmed crash.
The record
- CVE
- CVE-2026-97971
- Published
- Sep 25, 2026
- Updated
- Sep 25, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 25, 2026CVE publishedPublication date reported by the CVE source.
- Sep 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=6.19
- Affected versionversion=76b6f5dfb3fda76fce1f9990d6fa58adc711122b <56ea4e86832d8abe8930394473566c194d189f85
- Affected versionversion=76b6f5dfb3fda76fce1f9990d6fa58adc711122b <9e673bf5d88aa898e52cef5c87058c3fa845bc71
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
- Unprivileged listns and mount-namespace churn reproducerproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Get started to see how Hinoki identifies affected software and validates exploitability in your environment.
Get started