Medium 5.5Published Apr 24, 2026

CVE-2026-31664xfrm: clear trailing padding in build_polexpire()

Updated under an hour ago (Oct 27, 2026, 6:50 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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().

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Oct 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before a5127501c8d30b5728791b1e340284ca5c9cc4bd; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before e6f4ffe8596947a595c9544e73a73adcb0568b88; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before ac6985903db047eaff54db929e4bf6b06782788e; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before c221ed63a2769a0af8bd849dfe25740048f34ef4; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before eda30846ea54f8ed218468e5480c8305ca645e37; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before b1dfd6b27df35ef4f87825aa5f607378d23ff0f2; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before e1af65c669ebb1666c54576614c01a7f9ffcfff6; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 71a98248c63c535eaa4d4c22f099b68d902006d0	CNA record
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
linux linux_kernel linux:linux_kernel	from 2.6.12.1 before 6.1.169; from 6.2 before 6.6.135; from 6.7 before 6.12.82; from 6.13 before 6.18.23; from 6.19 before 6.19.13; 2.6.12; 2.6.12; 2.6.12; and 9 more ranges	NVD

References

References

https://git.kernel.org/stable/c/a5127501c8d30b5728791b1e340284ca5c9cc4bd
https://git.kernel.org/stable/c/e6f4ffe8596947a595c9544e73a73adcb0568b88
https://git.kernel.org/stable/c/ac6985903db047eaff54db929e4bf6b06782788e	patch
https://git.kernel.org/stable/c/c221ed63a2769a0af8bd849dfe25740048f34ef4	patch
https://git.kernel.org/stable/c/eda30846ea54f8ed218468e5480c8305ca645e37	patch
https://git.kernel.org/stable/c/b1dfd6b27df35ef4f87825aa5f607378d23ff0f2	patch
https://git.kernel.org/stable/c/e1af65c669ebb1666c54576614c01a7f9ffcfff6	patch
https://git.kernel.org/stable/c/71a98248c63c535eaa4d4c22f099b68d902006d0	patch
https://cert-portal.siemens.com/productcert/html/ssa-019113.html
https://cert-portal.siemens.com/productcert/html/ssa-082556.html
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The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.