CVE-2026-63952

HIGH

MEDIUM Priority: 0.01 BB Relevance: 42/100

Published: 2026-07-19 Modified: 2026-10-28 First seen: 2026-10-29 Status: active

Attack Surface

Low Complexity No Interaction Conf. Impact Integ. Impact Scope Change

CVSS Vector Breakdown

AV: Local

AC: Low

PR: Low

UI: None

S: Changed

C: High

I: High

A: None

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.