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CVE-2026-63952

memfd: deny writeable mappings when implying SEAL_WRITE PUBLISHED

Description (CNA)

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 (CNA)

Vendor / productVersions
Linux / Linuxaffected c4f75bc8bd6b3d62665e1f5400c419540edb5601 before b3f4f82d1315f1439059a83d1c22c51a5b43d99e; affected c4f75bc8bd6b3d62665e1f5400c419540edb5601 before 3be2a24f7f72ad7321ed6ad1715b956a4527bcf4; affected c4f75bc8bd6b3d62665e1f5400c419540edb5601 before 0995d1f79aed8ccbf62056189dd53fd19726ea08; affected c4f75bc8bd6b3d62665e1f5400c419540edb5601 before 555702282d4536a865dfffb1cd4f6028f196e7e8; affected c4f75bc8bd6b3d62665e1f5400c419540edb5601 before 3b041514cb6eae45869b020f743c14d983363222
Linux / Linuxaffected 6.3; unaffected 0 before 6.3; unaffected 6.6.143 through 6.6.*; unaffected 6.12.93 through 6.12.*; unaffected 6.18.35 through 6.18.*; unaffected 7.0.12 through 7.0.*; unaffected 7.1 through *

CWE

No CWE identifiers supplied.

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.