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NVD / CVE Program· CNA Linux

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

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 0616314b3b34f24cbb91da8c6bd8bcdc4c8592f9, 0a30dceb0e1f0c480d2482e6d7cebf8aebb6eb72, 6c55714c931051cd7f4839c19ce0867179fd22fe; azl3 kernel 6.6.134.1-2 on Azure Linux 3.0 6.6.137.1-1; cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0 Release Notes.

Low priority for now. Upgrade to Linux Linux 0616314b3b34f24cbb91da8c6bd8bcdc4c8592f9, 0a30dceb0e1f0c480d2482e6d7cebf8aebb6eb72, 6c55714c931051cd7f4839c19ce0867179fd22fe; azl3 kernel 6.6.134.1-2 on Azure Linux 3.0 6.6.137.1-1; cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0 Release Notes or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Apr 24, 2026
Updated
Nov 6, 2026
EPSS
0.1% · 1th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-31671

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel2.6.19.1 and later · before 5.10.253
  • linux linux kernel5.11 and later · before 5.15.203
  • linux linux kernel5.16 and later · before 6.1.169
  • linux linux kernel6.2 and later · before 6.6.135
  • linux linux kernel6.7 and later · before 6.12.82
  • linux linux kernel6.13 and later · before 6.18.23
  • linux linux kernel6.19 and later · before 6.19.13
  • linux linux kernel2.6.19
  • linux linux kernel7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.19affected
    • 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5 and later · before d27c02eec529f78055a46a5c9e6c62684382b2d8affected · git
    • 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5 and later · before 716c546e88cfe49d841658240e10cb57bc50a2ccaffected · git
    • 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5 and later · before 0616314b3b34f24cbb91da8c6bd8bcdc4c8592f9affected · git
    • 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5 and later · before e0c8542c3d097ed4205ded51868195d5d6ddac62affected · git
    • 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5 and later · before ff5ee507302303b15859753c3e0d67d38fd12c88affected · git
    • 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5 and later · before 6c55714c931051cd7f4839c19ce0867179fd22feaffected · git
    • 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5 and later · before 0a30dceb0e1f0c480d2482e6d7cebf8aebb6eb72affected · git
    • 97a64b4577ae2bc5599dbd008a3cd9e25de9b9f5 and later · before d10119968d0e1f2b669604baf2a8b5fdb72fa6b4affected · git
    • before 2.6.19not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.170-16.1.170-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.19.13-16.19.13-1
openSUSE:Leap 16.0dtb-aarch64before 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-64kbbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-azurebefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-defaultbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-default-basebefore 6.12.0-160000.35.1.160000.2.166.12.0-160000.35.1.160000.2.16
openSUSE:Leap 16.0kernel-docsbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-kvmsmallbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-obs-buildbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-obs-qabefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-rtbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-sourcebefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-symsbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-zfcpdumpbefore 6.12.0-160000.35.16.12.0-160000.35.1
SUSE:Linux Enterprise High Availability Extension 16.0kernel-defaultbefore 6.12.0-160000.35.16.12.0-160000.35.1
SUSE:Linux Enterprise Server 16.0kernel-azurebefore 6.12.0-160000.35.16.12.0-160000.35.1
SUSE:Linux Enterprise Server 16.0kernel-docsbefore 6.12.0-160000.35.16.12.0-160000.35.1
SUSE:Linux Enterprise Server 16.0kernel-kvmsmallbefore 6.12.0-160000.35.16.12.0-160000.35.1
SUSE:Linux Enterprise Server 16.0kernel-obs-qabefore 6.12.0-160000.35.16.12.0-160000.35.1
SUSE:Linux Enterprise Server 16.0kernel-zfcpdumpbefore 6.12.0-160000.35.16.12.0-160000.35.1
SUSE:Linux Micro 6.2kernel-64kbbefore 6.12.0-160000.35.16.12.0-160000.35.1
SUSE:Linux Micro 6.2kernel-default-basebefore 6.12.0-160000.35.1.160000.2.166.12.0-160000.35.1.160000.2.16

+4

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-31669Apr 24, 2026 · mptcp: fix slab-use-after-free in __inet_lookup_established
    39Monitor
  • ← EarlierCVE-2026-31670Apr 24, 2026 · net: rfkill: prevent unlimited numbers of rfkill events from being created
    22Monitor
  • Later →CVE-2026-31672Apr 24, 2026 · wifi: rt2x00usb: fix devres lifetime
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0616314b3b34f24cbb91da8c6bd8bcdc4c8592f9Vendor (CNA)
Linux Linux0a30dceb0e1f0c480d2482e6d7cebf8aebb6eb72Vendor (CNA)
Linux Linux6c55714c931051cd7f4839c19ce0867179fd22feVendor (CNA)
Linux Linux716c546e88cfe49d841658240e10cb57bc50a2ccVendor (CNA)
Linux Linuxd10119968d0e1f2b669604baf2a8b5fdb72fa6b4Vendor (CNA)
Linux Linuxd27c02eec529f78055a46a5c9e6c62684382b2d8Vendor (CNA)
Linux Linuxe0c8542c3d097ed4205ded51868195d5d6ddac62Vendor (CNA)
Linux Linuxff5ee507302303b15859753c3e0d67d38fd12c88Vendor (CNA)
azl3 kernel 6.6.134.1-2 on Azure Linux 3.06.6.137.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0Release NotesMicrosoft (MSRC)
debian:linux6.1.170-1 · Debian:12Package registry (OSV)
opensuse:dtb-aarch646.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-64kb6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-azure6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-default6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-default-base6.12.0-160000.35.1.160000.2.16 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-docs6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-kvmsmall6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-obs-build6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-obs-qa6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-rt6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-source6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-syms6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
suse:kernel-64kb6.12.0-160000.35.1 · SUSE:Linux Micro 6.2Package registry (OSV)
suse:kernel-azure6.12.0-160000.35.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)
suse:kernel-default6.12.0-160000.35.1 · SUSE:Linux Enterprise High Availability Extension 16.0Package registry (OSV)
suse:kernel-default-base6.12.0-160000.35.1.160000.2.16 · SUSE:Linux Micro 6.2Package registry (OSV)
suse:kernel-docs6.12.0-160000.35.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)
suse:kernel-kvmsmall6.12.0-160000.35.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)
suse:kernel-obs-build6.12.0-160000.35.1 · SUSE:Linux Micro Extras 6.2Package registry (OSV)

+5

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-401 · Missing Release of Memory after Effective Lifetime

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (10 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records