Kernel crash via zero-length BPF packet redirect
Published Jun 18, 2025 · Updated May 11, 2026
NULL pointer dereference in the Linux kernel allows local users to crash the kernel through a privileged zero-length BPF packet redirect. bpf_prog_test_run_skb() forwards an empty skb without validating its modified pkt_len, leaving fq_codel_drop() to dereference a null flow head. The path requires CAP_BPF or CAP_SYS_ADMIN in the initial user namespace, and successful exploitation interrupts the host by crashing its kernel.
Summary
What happened
NULL pointer dereference in the Linux kernel allows local users to crash the kernel through a privileged zero-length BPF packet redirect. bpf_prog_test_run_skb() forwards an empty skb without validating its modified pkt_len, leaving fq_codel_drop() to dereference a null flow head. The path requires CAP_BPF or CAP_SYS_ADMIN in the initial user namespace, and successful exploitation interrupts the host by crashing its kernel.
The record
- CVE
- CVE-2022-49975
- Published
- Jun 18, 2025
- Updated
- May 11, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499.004
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Jun 18, 2025CVE publishedPublication date reported by the CVE source.
- May 11, 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=4.9
- Affected versionversion=5293efe62df81908f2e90c9820c7edcc8e61f5e9 <6204bf78b2a903b96ba43afff6abc0b04d6e0462
- Affected versionversion=5293efe62df81908f2e90c9820c7edcc8e61f5e9 <72f2dc8993f10262092745a88cb2dd0fef094f23
- Affected versionversion=5293efe62df81908f2e90c9820c7edcc8e61f5e9 <8b68e53d56697a59b5c53893b53f508bbdf272a0
- Affected versionversion=5293efe62df81908f2e90c9820c7edcc8e61f5e9 <a75987714bd2d8e59840667a28e15c1fa5c47554
- Affected versionversion=5293efe62df81908f2e90c9820c7edcc8e61f5e9 <fd1894224407c484f652ad456e1ce423e89bb3eb
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
- syzbot fq_codel_drop crash reproducersproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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