SEPTEMBER 8, 2026
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Case File

CVE-2026-63952

HIGH · CVSS 8.4 EPSS 0.16%

Source: NVD + CISA KEV + EPSS · Published 2026-07-19 · Last synced 2026-08-18

CyberRota Analysis

AI-Generated

The vulnerability affects the Linux kernel's memory file descriptor (memfd) functionality, where the SEAL_WRITE protection can be bypassed due to a timing issue with the application of implied seals. This flaw allows an attacker to modify a memory file descriptor that should be write-sealed, potentially leading to unauthorized data manipulation or code execution. Organizations using affected Linux kernel versions should prioritize patching this vulnerability to safeguard against potential exploitation.

CVE
CVE-2026-63952
Severity
HIGH
CVSS
8.4
EPSS
0.16%
Linux

Original NVD 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.