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CVE-2026-63952

8.4 · HIGH

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.

Published Jul 19, 2026EPSS 0.16%

Overview

CVE-2026-63952 is a high-severity vulnerability. It was published on July 19, 2026 and has a CVSS 3.1 base score of 8.4 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.4, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/0995d1f79aed8ccbf62056189dd53fd19726ea08Refgit.kernel.org/stable/c/3b041514cb6eae45869b020f743c14d983363222Refgit.kernel.org/stable/c/3be2a24f7f72ad7321ed6ad1715b956a4527bcf4Refgit.kernel.org/stable/c/555702282d4536a865dfffb1cd4f6028f196e7e8Refgit.kernel.org/stable/c/b3f4f82d1315f1439059a83d1c22c51a5b43d99e

How CyberStrike helps

Frequently asked questions

What is CVE-2026-63952?

CVE-2026-63952 is a high-severity vulnerability. It was published on July 19, 2026 and has a CVSS 3.1 base score of 8.4 (HIGH).

How severe is CVE-2026-63952?

This vulnerability has a CVSS 3.1 base score of 8.4, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-63952?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-63952?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-63952 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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