CVE-2026-63952 Details
Description
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.
A vulnerability in the Linux kernel's handling of memory file descriptors (memfd) allows writable mappings to persist even when SEAL_WRITE is supposedly applied. This issue arises because the SEAL_EXEC seal, which implies SEAL_WRITE, is added after a check that prevents writable mappings. As a result, an attacker could exploit this behavior to modify a memfd that appears to be write-sealed. The vulnerability affects the Linux kernel's stable releases.
The vulnerability has been addressed by modifying the order in which the implied seals are applied, ensuring that SEAL_WRITE is correctly enforced before any writable mappings can be established.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
No SSVC data is available for this CVE.
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Weakness Enumeration
No weakness enumeration is available for this CVE.
Affected Products
No affected product data is available for this CVE.
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 20, 2026 | CVE Modified | kernel.org |
| Jul 19, 2026 | New CVE Received | kernel.org |