CVE-2026-63952
In the Linux kernel, the following vulnerability has been resolved: memfd: deny writeable mappings when implying SEAL_WRITE When SEAL_EXEC is added, SEAL_WRITE is implied to make W^X. But the implied seal is set after the check that makes sure the memfd can not have any writable mappings. This means one can use SEAL_EXEC to apply SEAL_WRITE while having writeable mappings. This breaks the contract that SEAL_WRITE provides and can be used by an attacker to pass a memfd that appears to be write sealed but can still be modified arbitrarily. Fix this by adding the implied seals before the call for mapping_deny_writable() is done.
Affected versions
Linux kernel versions
6.3
and later are affected. Fixed in
6.6.143,
6.12.93,
6.18.35,
7.0.12,
7.1
and their respective stable series.
References
5 totalFrequently asked questions
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What is CVE-2026-63952?
CVE-2026-63952 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 6.3 onward and has been patched in 6.6.143, 6.12.93, 6.18.35 and others. CVE-2026-63952 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-2026-63952?
Yes — CVE-2026-63952 has been patched. Fixed versions include 6.6.143, 6.12.93, 6.18.35 and others. If you are running Linux kernel 6.3 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-63952 actively exploited?
No — CVE-2026-63952 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.