Kernel pointer forgery via imprecise verifier pruning
Published Sep 25, 2026 · Updated Sep 25, 2026
Improper verification in Linux 5.18.18 through 5.19 allows local users to forge kernel pointers through crafted eBPF programs. The check_map_kptr_access() path accepts a known-zero scalar for an untrusted kptr field without marking the register precise, so checkpoint pruning can skip a later path carrying attacker-controlled nonzero bits. Loading the crafted program requires CAP_BPF or CAP_SYS_ADMIN when unprivileged bpf() calls are disabled; acceptance lets those bits be read back as a trusted PTR_TO_BTF_ID.
Summary
What happened
Improper verification in Linux 5.18.18 through 5.19 allows local users to forge kernel pointers through crafted eBPF programs. The check_map_kptr_access() path accepts a known-zero scalar for an untrusted kptr field without marking the register precise, so checkpoint pruning can skip a later path carrying attacker-controlled nonzero bits. Loading the crafted program requires CAP_BPF or CAP_SYS_ADMIN when unprivileged bpf() calls are disabled; acceptance lets those bits be read back as a trusted PTR_TO_BTF_ID.
The record
- CVE
- CVE-2026-98034
- Published
- Sep 25, 2026
- Updated
- Sep 25, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- Unavailable
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
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=5.18.18 <5.19
- Affected versionversion=5.19
- Affected versionversion=61df10c7799e27807ad5e459eec9d77cddf8bf45 <86168208737bdd267d92d855d453d1d2f840df19
- Affected versionversion=61df10c7799e27807ad5e459eec9d77cddf8bf45 <ecdc5043794c9184aa8e6c814603899479c46b35
- Affected versionversion=b5a8069835e5236824a84281592d29f859b33153
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
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Technologies
Your stack
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Your stack
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