Memory corruption via unsafe IPv4 FIB refcounting
Published Aug 15, 2026 · Updated Aug 15, 2026
Use-after-free in the Linux kernel IPv4 FIB 4.10 through 7.1.4 allows local users to corrupt kernel memory during FIB notifier dumps. fib_leaf_notify() walks fib_info objects under RCU without guaranteeing their lifetime, while notifier callbacks increment a reference count that can already be zero. The documented trigger occurs during network-namespace cleanup with a FIB notifier registered, and the public report demonstrates a refcount warning rather than a weaponized exploit.
Summary
What happened
Use-after-free in the Linux kernel IPv4 FIB 4.10 through 7.1.4 allows local users to corrupt kernel memory during FIB notifier dumps. fib_leaf_notify() walks fib_info objects under RCU without guaranteeing their lifetime, while notifier callbacks increment a reference count that can already be zero. The documented trigger occurs during network-namespace cleanup with a FIB notifier registered, and the public report demonstrates a refcount warning rather than a weaponized exploit.
The record
- CVE
- CVE-2026-74289
- Published
- Aug 15, 2026
- Updated
- Aug 15, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 15, 2026CVE publishedPublication date reported by the CVE source.
- Aug 15, 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=4.10
- Affected versionversion=c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea <06b693d2eb6651a63ad85bad8673de3b7d4edd6d
- Affected versionversion=c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea <676482da8d938ea72c26da0fc86af2d2ec238ab2
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
No public exploit references are available in this record.
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
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo