CVE-2026-63952 Affecting kernel-kvmsmall package, versions <6.12.0-160000.37.1


Severity

Recommended
0.0
high
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.16% (7th percentile)

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  • Snyk IDSNYK-SLES1600-KERNELKVMSMALL-19333894
  • published27 Aug 2026
  • disclosed11 Aug 2026

Introduced: 11 Aug 2026

NewCVE-2026-63952  (opens in a new tab)

How to fix?

Upgrade SLES:16.0.0 kernel-kvmsmall to version 6.12.0-160000.37.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-kvmsmall package and not the kernel-kvmsmall package as distributed by SLES. See How to fix? for SLES:16.0.0 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1