Riskcovery

CVE-2026-63952

memfd: deny writeable mappings when implying SEAL_WRITE

State
Published
Severity
8.4 High
Published
Jul 19, 2026
Updated
Oct 19, 2026
Reserved
Jul 19, 2026

Read the record on cve.org

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.

Scores

CVSSScoreVectorSource
3.18.4 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:NLinux

Weaknesses

  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Affected Products

ProductVersions
LinuxLinux
  • c4f75bc8bd6b3d62665e1f5400c419540edb5601 to before b3f4f82d1315f1439059a83d1c22c51a5b43d99eAffected
  • c4f75bc8bd6b3d62665e1f5400c419540edb5601 to before 3be2a24f7f72ad7321ed6ad1715b956a4527bcf4Affected
  • c4f75bc8bd6b3d62665e1f5400c419540edb5601 to before 0995d1f79aed8ccbf62056189dd53fd19726ea08Affected
  • c4f75bc8bd6b3d62665e1f5400c419540edb5601 to before 555702282d4536a865dfffb1cd4f6028f196e7e8Affected
  • c4f75bc8bd6b3d62665e1f5400c419540edb5601 to before 3b041514cb6eae45869b020f743c14d983363222Affected
LinuxLinux
  • 6.3Affected
  • before 6.3Not affected
  • 6.6.143 through 6.6.*Not affected
  • 6.12.93 through 6.12.*Not affected
  • 6.18.35 through 6.18.*Not affected
  • 7.0.12 through 7.0.*Not affected
  • 7.1 and laterNot affected

References

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