CVE-2026-72423
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk5th percentile - higher than 5% of all known CVEs
Summary
In the Linux kernel BPF mechanism, conntrack lookup and allocation kfuncs take an opts pointer and an opts__sz argument. The verifier checks only the memory range described by opts__sz, but the wrappers unconditionally write opts->error whenever the internal helper returns an error. For an invalid size smaller than the end of opts->error, that write can land outside the verifier-checked range. The fix keeps returning NULL for invalid arguments, but only reports the error through opts->error when the supplied size includes the field.
Risk Assessment
This may lead to out-of-bounds memory write, potentially causing data corruption or privilege escalation.
Recommendation
Update the Linux kernel to a version with the fix, and avoid using invalid opts sizes in BPF programs.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: bpf: Guard conntrack opts error writes The conntrack lookup and allocation kfuncs take an opts pointer together with an opts__sz argument. The verifier checks only the memory range described by opts__sz, but the wrappers unconditionally write opts->error whenever the internal lookup or allocation helper returns an error. For an invalid size smaller than the end of opts->error, that write can land outside the verifier-checked range. Keep returning NULL for invalid arguments, but only report the error through opts->error when the supplied size includes the field. This preserves error reporting for the supported 12-byte and 16-byte layouts, and for other invalid sizes that still include opts->error.