CVE-2026-63952memfd: deny writeable mappings when implying SEAL_WRITE
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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.
- CVSS
- 8.4 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Awaiting Analysis
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from c4f75bc8bd6b3d62665e1f5400c419540edb5601 before b3f4f82d1315f1439059a83d1c22c51a5b43d99e; from c4f75bc8bd6b3d62665e1f5400c419540edb5601 before 3be2a24f7f72ad7321ed6ad1715b956a4527bcf4; from c4f75bc8bd6b3d62665e1f5400c419540edb5601 before 0995d1f79aed8ccbf62056189dd53fd19726ea08; from c4f75bc8bd6b3d62665e1f5400c419540edb5601 before 555702282d4536a865dfffb1cd4f6028f196e7e8; from c4f75bc8bd6b3d62665e1f5400c419540edb5601 before 3b041514cb6eae45869b020f743c14d983363222 | CNA record |
References
- https://git.kernel.org/stable/c/b3f4f82d1315f1439059a83d1c22c51a5b43d99e
- https://git.kernel.org/stable/c/3be2a24f7f72ad7321ed6ad1715b956a4527bcf4
- https://git.kernel.org/stable/c/0995d1f79aed8ccbf62056189dd53fd19726ea08
- https://git.kernel.org/stable/c/555702282d4536a865dfffb1cd4f6028f196e7e8
- https://git.kernel.org/stable/c/3b041514cb6eae45869b020f743c14d983363222
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.