Local privilege escalation via unvalidated BPF helper prototype
Published Oct 15, 2025 · Updated Oct 15, 2025
Improper BPF verifier validation in Linux 5.8 through 6.16.9 allows local users to disclose or corrupt kernel memory via a crafted program. When a disabled helper leaves its function pointer NULL, get_helper_proto accepts the prototype and treats zeroed argument metadata as ARG_DONTCARE, allowing bpf_get_branch_snapshot to copy branch records to an unvalidated destination. Loading the program requires CAP_PERFMON or CAP_BPF; successful use exposes kernel addresses, permits kernel-memory writes, and can panic the host.
Summary
What happened
Improper BPF verifier validation in Linux 5.8 through 6.16.9 allows local users to disclose or corrupt kernel memory via a crafted program. When a disabled helper leaves its function pointer NULL, get_helper_proto accepts the prototype and treats zeroed argument metadata as ARG_DONTCARE, allowing bpf_get_branch_snapshot to copy branch records to an unvalidated destination. Loading the program requires CAP_PERFMON or CAP_BPF; successful use exposes kernel addresses, permits kernel-memory writes, and can panic the host.
The record
- CVE
- CVE-2025-39990
- Published
- Oct 15, 2025
- Updated
- Oct 15, 2025
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Oct 15, 2025CVE publishedPublication date reported by the CVE source.
- Oct 15, 2025Record 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3d429cb1278e995e22995ef117fa96d223a67e93
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6233715b4b714068d6c831d214a4e8792109875a
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e4414b01c1cd9887bbde92f946c1ba94e40d6d64
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
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