CVE-2026-46099Network attack vector

Remote kernel crash via IPv6 lwtunnel race

Published May 27, 2026 · Updated May 27, 2026

Use-after-free in Linux Kernel IPv6 lwtunnels allows remote attackers to crash the kernel via crafted IPv6 traffic. The seg6_input_core() and rpl_input() paths cache a NOREF route after ip6_route_input(), allowing a concurrent FIB lookup to free pcpu_rt before dst_hold() takes a reference. Reachability requires PREEMPT_RT without PREEMPT_RT_NEEDS_BH_LOCK, a configured SRv6 or RPL-encap route, shared nexthops, and a successful race against a higher-priority same-CPU task.

CVSS severity8.1
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux Kernel IPv6 lwtunnels allows remote attackers to crash the kernel via crafted IPv6 traffic. The seg6_input_core() and rpl_input() paths cache a NOREF route after ip6_route_input(), allowing a concurrent FIB lookup to free pcpu_rt before dst_hold() takes a reference. Reachability requires PREEMPT_RT without PREEMPT_RT_NEEDS_BH_LOCK, a configured SRv6 or RPL-encap route, shared nexthops, and a successful race against a higher-priority same-CPU task.

The record

CVE
CVE-2026-46099
Published
May 27, 2026
Updated
May 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-911, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=4.12
  2. Affected versionversion=af4a2209b1344939eaac11f269c261d347cbc3ee <52f9db67f8f35f436366cf4980b4f0a2583d0ef0
  3. Affected versionversion=af4a2209b1344939eaac11f269c261d347cbc3ee <6bd17925bd6866027a6555db17905b9fc073d38d
  4. Affected versionversion=af4a2209b1344939eaac11f269c261d347cbc3ee <9dd5481f960e337b81d7dfe429529495c1c481c0
  5. Affected versionversion=af4a2209b1344939eaac11f269c261d347cbc3ee <b778b6d095421619c331fd2d7751143cd5387103
  6. Affected versionversion=af4a2209b1344939eaac11f269c261d347cbc3ee <f9c52a6ba9780bd27e0bf4c044fd91c13c778b6e

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=4.12; version=af4a2209b1344939eaac11f269c261d347cbc3ee <52f9db67f8f35f436366cf4980b4f0a2583d0ef0; version=af4a2209b1344939eaac11f269c261d347cbc3ee <6bd17925bd6866027a6555db17905b9fc073d38d; version=af4a2209b1344939eaac11f269c261d347cbc3ee <9dd5481f960e337b81d7dfe429529495c1c481c0; version=af4a2209b1344939eaac11f269c261d347cbc3ee <b778b6d095421619c331fd2d7751143cd5387103; version=af4a2209b1344939eaac11f269c261d347cbc3ee <f9c52a6ba9780bd27e0bf4c044fd91c13c778b6e

Published CVSS scores

7.3Red Hat SADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H
8.1kernel.orgCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-911Improper Update of Reference Count
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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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