In the Linux kernel, the following vulnerability has been resolved:

xfrm: clear trailing padding in build_polexpire()

build_expire() clears the trailing padding bytes of struct
xfrm_user_expire after setting the hard field via memset_after(),
but the analogous function build_polexpire() does not do this for
struct xfrm_user_polexpire.

The padding bytes after the __u8 hard field are left
uninitialized from the heap allocation, and are then sent to
userspace via netlink multicast to XFRMNLGRP_EXPIRE listeners,
leaking kernel heap memory contents.

Add the missing memset_after() call, matching build_expire().

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Linux Linux unaffected
Version Status Constraints
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < ac6985903db047eaff54db929e4bf6b06782788e
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < c221ed63a2769a0af8bd849dfe25740048f34ef4
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < eda30846ea54f8ed218468e5480c8305ca645e37
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < b1dfd6b27df35ef4f87825aa5f607378d23ff0f2
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < e1af65c669ebb1666c54576614c01a7f9ffcfff6
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < 71a98248c63c535eaa4d4c22f099b68d902006d0
Linux Linux affected
Version Status Constraints
2.6.12 affected —
0 unaffected < 2.6.12
6.1.169 unaffected ≤ 6.1.*
6.6.135 unaffected ≤ 6.6.*
6.12.82 unaffected ≤ 6.12.*
6.18.23 unaffected ≤ 6.18.*
6.19.13 unaffected ≤ 6.19.*
7.0 unaffected ≤ *

No data.

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://git.kernel.org/stable/c/71a98248c63c535eaa4d4c22f099b68d902006d0 cve-icon cve-icon
https://git.kernel.org/stable/c/ac6985903db047eaff54db929e4bf6b06782788e cve-icon cve-icon
https://git.kernel.org/stable/c/b1dfd6b27df35ef4f87825aa5f607378d23ff0f2 cve-icon cve-icon
https://git.kernel.org/stable/c/c221ed63a2769a0af8bd849dfe25740048f34ef4 cve-icon cve-icon
https://git.kernel.org/stable/c/e1af65c669ebb1666c54576614c01a7f9ffcfff6 cve-icon cve-icon
https://git.kernel.org/stable/c/eda30846ea54f8ed218468e5480c8305ca645e37 cve-icon cve-icon
https://lore.kernel.org/linux-cve-announce/2026042405-CVE-2026-31664-d315@gregkh/T cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-31664 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-31664 cve-icon
History

Sat, 25 Apr 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-908
References
Metrics threat_severity

None

 cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Low

Fri, 24 Apr 2026 15:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: xfrm: clear trailing padding in build_polexpire() build_expire() clears the trailing padding bytes of struct xfrm_user_expire after setting the hard field via memset_after(), but the analogous function build_polexpire() does not do this for struct xfrm_user_polexpire. The padding bytes after the __u8 hard field are left uninitialized from the heap allocation, and are then sent to userspace via netlink multicast to XFRMNLGRP_EXPIRE listeners, leaking kernel heap memory contents. Add the missing memset_after() call, matching build_expire().
Title xfrm: clear trailing padding in build_polexpire()
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-04-24T14:45:13.922Z

Reserved: 2026-03-09T15:48:24.129Z

Link: CVE-2026-31664

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-04-24T15:16:46.043

Modified: 2026-04-24T17:51:40.810

Link: CVE-2026-31664

cve-icon Redhat

Severity : Low

Publid Date: 2026-04-24T00:00:00Z

Links: CVE-2026-31664 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses