VulnerabilityPublished 24 Apr 2026Updated 6 Nov 2026

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

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in ff5ee507302303b15859753c3e0d67d38fd12c88 : update Linux kernel when convenient.

Data as of 6 Nov 2026, 15:49 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-06.

Patch

Available – fixed in ff5ee507302303b15859753c3e0d67d38fd12c88, e0c8542c3d097ed4205ded51868195d5d6ddac62, d10119968d0e1f2b669604baf2a8b5fdb72fa6b4 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5, < ff5ee507302303b15859753c3e0d67d38fd12c88	Fixed in ff5ee507302303b15859753c3e0d67d38fd12c88
LinuxLinux	Affected ≥ 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5, < e0c8542c3d097ed4205ded51868195d5d6ddac62	Fixed in e0c8542c3d097ed4205ded51868195d5d6ddac62
LinuxLinux	Affected ≥ 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5, < d10119968d0e1f2b669604baf2a8b5fdb72fa6b4	Fixed in d10119968d0e1f2b669604baf2a8b5fdb72fa6b4
LinuxLinux	Affected ≥ 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5, < d27c02eec529f78055a46a5c9e6c62684382b2d8	Fixed in d27c02eec529f78055a46a5c9e6c62684382b2d8
LinuxLinux	Affected ≥ 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5, < 0616314b3b34f24cbb91da8c6bd8bcdc4c8592f9	Fixed in 0616314b3b34f24cbb91da8c6bd8bcdc4c8592f9
LinuxLinux	Affected ≥ 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5, < 716c546e88cfe49d841658240e10cb57bc50a2cc	Fixed in 716c546e88cfe49d841658240e10cb57bc50a2cc

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.

References

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