CVE-2025-71085Public exploit

Kernel crash via negative headroom calculation

Published Jan 13, 2026 · Updated Jan 13, 2026

Reachable assertion in the CALIPSO IPv6 path in the Linux Kernel allows local users to crash the kernel via a crafted sendmsg call. __skb_cow implicitly casts an oversized unsigned headroom sum to a negative integer, causing calipso_skbuff_setattr to pass a negative nhead value to pskb_expand_head and trigger BUG_ON. The trigger requires a configured CALIPSO NetLabel mapping and a crafted IPv6 hop-by-hop control message; the bounded result is a kernel oops and service interruption.

CVSS severity7.5
High
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in the CALIPSO IPv6 path in the Linux Kernel allows local users to crash the kernel via a crafted sendmsg call. __skb_cow implicitly casts an oversized unsigned headroom sum to a negative integer, causing calipso_skbuff_setattr to pass a negative nhead value to pskb_expand_head and trigger BUG_ON. The trigger requires a configured CALIPSO NetLabel mapping and a crafted IPv6 hop-by-hop control message; the bounded result is a kernel oops and service interruption.

The record

CVE
CVE-2025-71085
Published
Jan 13, 2026
Updated
Jan 13, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-617, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 <2bb759062efa188ea5d07242a43e5aa5464bbae1
  2. Affected versionversion=2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 <58fc7342b529803d3c221101102fe913df7adb83
  3. Affected versionversion=2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 <73744ad5696dce0e0f43872aba8de6a83d6ad570
  4. Affected versionversion=2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 <bf3709738d8a8cc6fa275773170c5c29511a0b24
  5. Affected versionversion=2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 <c53aa6a5086f03f19564096ee084a202a8c738c0
  6. Affected versionversion=4.8

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 <2bb759062efa188ea5d07242a43e5aa5464bbae1; version=2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 <58fc7342b529803d3c221101102fe913df7adb83; version=2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 <73744ad5696dce0e0f43872aba8de6a83d6ad570; version=2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 <bf3709738d8a8cc6fa275773170c5c29511a0b24; version=2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 <c53aa6a5086f03f19564096ee084a202a8c738c0; version=4.8

Published CVSS scores

5.5NIST National Vulnerability DatabaseCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.5kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-617Reachable Assertion
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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