What’s Vulnerable › Vulnerabilities

CVE-2026-31671: xfrm_user: fix info leak in build_report()

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-24 · updated 2026-10-15
• Weakness: CWE-401

Description

In the Linux kernel, the following vulnerability has been resolved: xfrm_user: fix info leak in build_report() struct xfrm_user_report is a __u8 proto field followed by a struct xfrm_selector which means there is three "empty" bytes of padding, but the padding is never zeroed before copying to userspace. Fix that up by zeroing the structure before setting individual member variables.

Affected products

• Linux kernel: from 2.6.19.1 before 5.10.253; from 5.11 before 5.15.203; from 5.16 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 — fixed in 5.10.253, 5.15.203, 6.1.169, 6.12.82, 6.18.23, 6.19.13

How to fix

Upgrade to a fixed version: Linux kernel 5.10.253, 5.15.203, 6.1.169, 6.12.82. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/0616314b3b34f24cbb91da8c6bd8bcdc4c8592f9
• https://git.kernel.org/stable/c/0a30dceb0e1f0c480d2482e6d7cebf8aebb6eb72
• https://git.kernel.org/stable/c/6c55714c931051cd7f4839c19ce0867179fd22fe
• https://git.kernel.org/stable/c/716c546e88cfe49d841658240e10cb57bc50a2cc
• https://git.kernel.org/stable/c/d10119968d0e1f2b669604baf2a8b5fdb72fa6b4
• https://git.kernel.org/stable/c/d27c02eec529f78055a46a5c9e6c62684382b2d8
• https://git.kernel.org/stable/c/e0c8542c3d097ed4205ded51868195d5d6ddac62
• https://git.kernel.org/stable/c/ff5ee507302303b15859753c3e0d67d38fd12c88
• https://cert-portal.siemens.com/productcert/html/ssa-019113.html
• https://cert-portal.siemens.com/productcert/html/ssa-082556.html
• https://cert-portal.siemens.com/productcert/html/ssa-457936.html

Get alerted when CVE-2026-31671 or the next vulnerability affects your stack