CVE Catalog

CVE-2026-63952

HighCVSS 8.4
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.16%

6th percentile - higher than 6% of all known CVEs

Summary

In the Linux kernel, a vulnerability in memfd allows SEAL_WRITE to be implied via SEAL_EXEC before checking for existing writable mappings, breaking the write-seal contract. This enables an attacker to pass a memfd that appears write-sealed but remains modifiable.

Risk Assessment

An attacker can exploit this to bypass write protection on memfd, leading to data integrity violations and potential privilege escalation.

Recommendation

Update the Linux kernel to a version that fixes the order of implied seal setting before the writable mapping check.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS