CVE-2026-64036
In the Linux kernel, the following vulnerability has been resolved: cgroup/rstat: validate cpu before css_rstat_cpu() access css_rstat_updated() is exposed as a BPF kfunc and accepts a caller-provided cpu argument. The function uses cpu for per-cpu rstat lookups without checking whether it refers to a valid possible CPU. A BPF iter/cgroup program with CAP_BPF and CAP_PERFMON can pass an invalid cpu value. On an unfixed UBSCAN_BOUNDS test kernel, cpu == 0x7fffffff triggers: UBSAN: array-index-out-of-bounds in kernel/cgroup/rstat.c:31:9 index 2147483647 is out of range for type 'long unsigned int [64]' Call Trace: css_rstat_updated bpf_iter_run_prog cgroup_iter_seq_show bpf_seq_read Add cpu validation to the BPF-facing css_rstat_updated() kfunc and move the common implementation to __css_rstat_updated() for in-kernel callers.
Affected versions
Linux kernel versions
6.1
and later are affected. Fixed in
6.18.34,
7.0.11,
7.1
and their respective stable series.
References
3 totalFrequently asked questions
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What is CVE-2026-64036?
CVE-2026-64036 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 6.1 onward and has been patched in 6.18.34, 7.0.11 and 7.1. CVE-2026-64036 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-64036?
Yes — CVE-2026-64036 has been patched. Fixed versions include 6.18.34, 7.0.11 and 7.1. If you are running Linux kernel 6.1 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-64036 actively exploited?
No — CVE-2026-64036 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.