CVE-2026-64027
In the Linux kernel, the following vulnerability has been resolved: net: shaper: rework the VALID marking (again) Recent commit changed the semantics from NOT_VALID to VALID. I didn't realize that the flags are not stored atomically with the entry in XArray. There's still a race of reader observing a VALID mark for a slot, getting interrupted, writer replacing the entry with a different one, reader continuing, fetching the entry which is now a different pointer than the pointer for which VALID was meant. The biggest consequence of this is that we may see a UAF since net_shaper_rollback() assumed that entries without VALID can be freed without observing RCU. Looks like the XArray marks are buying us nothing at this point. Let's convert the code to an explicit valid field. The smp_load_acquire() / smp_store_release() barriers are marginally cleaner.
Affected versions
Linux kernel versions
6.13
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-2026-64027?
CVE-2026-64027 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 6.13 onward and has been patched in 6.18.34, 7.0.11 and 7.1. CVE-2026-64027 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-2026-64027?
Yes — CVE-2026-64027 has been patched. Fixed versions include 6.18.34, 7.0.11 and 7.1. If you are running Linux kernel 6.13 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-64027 actively exploited?
No — CVE-2026-64027 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.