Review reviewHigh

CVE-2026-63952

Linux

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...

CVSS: 8.4
EPSS: -
CISA KEV: Not listed
Published: 2026.07.20

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability-

Technical severityCVSS 8.4

Vulnerability overview

Affected product and versions

Product: Linux
Affected versions: >= c4f75bc8bd6b3d62665e1f5400c419540edb5601 < b3f4f82d1315f1439059a83d1c22c51a5b43d99e, >= c4f75bc8bd6b3d62665e1f5400c419540edb5601 < 3be2a24f7f72ad7321ed6ad1715b956a4527bcf4, >= c4f75bc8bd6b3d62665e1f5400c419540edb5601 < 0995d1f79aed8ccbf62056189dd53fd19726ea08, >= c4f75bc8bd6b3d62665e1f5400c419540edb5601 < 555702282d4536a865dfffb1cd4f6028f196e7e8, >= c4f75bc8bd6b3d62665e1f5400c419540edb5601 < 3b041514cb6eae45869b020f743c14d983363222, >= 6.3
Fixed versions: No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that Linux and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
CWE: Not available