CVE-2026-63952

HIGHCVSS 8.4/10EPSS 0.16%

Last modified

CVE-2026-63952 is a high-severity vulnerability rated 8.4/10 on the CVSS scale. 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. EPSS estimates a 0.16% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
8.4/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

EPSS Probability
0.16%

5.6th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= c4f75bc8bd6b3d62665e1f5400c419540edb5601, < b3f4f82d1315f1439059a83d1c22c51a5b43d99e; >= c4f75bc8bd6b3d62665e1f5400c419540edb5601, < 3be2a24f7f72ad7321ed6ad1715b956a4527bcf4; >= c4f75bc8bd6b3d62665e1f5400c419540edb5601, < 0995d1f79aed8ccbf62056189dd53fd19726ea08; >= c4f75bc8bd6b3d62665e1f5400c419540edb5601, < 555702282d4536a865dfffb1cd4f6028f196e7e8; >= c4f75bc8bd6b3d62665e1f5400c419540edb5601, < 3b041514cb6eae45869b020f743c14d983363222
LinuxLinux6.3

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-63952?
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.
How severe is CVE-2026-63952?
CVE-2026-63952 has a CVSS score of 8.4/10 (HIGH severity). The EPSS model estimates a 0.16% probability of exploitation in the next 30 days.
How do I fix CVE-2026-63952?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST