CVE-2026-64538

Kernel crash via unchecked IPv6 device pointer

Published Jul 27, 2026 · Updated Jul 27, 2026

NULL pointer dereference in the Linux Kernel IPv6 routing code allows remote attackers to crash the kernel via an ICMPv6 Router Advertisement. fib6_nh_mtu_change() re-fetches an IPv6 device pointer and reads idev->cnf.mtu6 without checking for NULL after interface teardown clears dev->ip6_ptr. Triggering requires a same-segment Router Advertisement during a narrow teardown race involving a nexthop-backed IPv6 route; the bounded consequence is a kernel oops or crash.

CVSS severity5.3
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in the Linux Kernel IPv6 routing code allows remote attackers to crash the kernel via an ICMPv6 Router Advertisement. fib6_nh_mtu_change() re-fetches an IPv6 device pointer and reads idev->cnf.mtu6 without checking for NULL after interface teardown clears dev->ip6_ptr. Triggering requires a same-segment Router Advertisement during a narrow teardown race involving a nexthop-backed IPv6 route; the bounded consequence is a kernel oops or crash.

The record

CVE
CVE-2026-64538
Published
Jul 27, 2026
Updated
Jul 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-476, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 27, 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=5.3
  2. Affected versionversion=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <1451deca9896957159f0666520a792c1b861af4f
  3. Affected versionversion=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <302d57ed7872838b40e56a868fb4c7da7da606e9
  4. Affected versionversion=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <46c3b8191aad3d032776bf3bebf03efdf5f4b905
  5. Affected versionversion=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <6428634f7a0b7878144b4925c37856bef3224967
  6. Affected versionversion=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <80600b5d0f3ecb9324120dc95b5e915130f516c5
  7. Affected versionversion=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <b0d0eb13a0441a8ebf4f227843deaf494f1e2c33
  8. Affected versionversion=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <b2c70dd3326809429b709a9c7e9220d29923051a
  9. Affected versionversion=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <d08d019f2f43a6f9a71e81868bbc326b3afaf37b

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.3; version=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <1451deca9896957159f0666520a792c1b861af4f; version=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <302d57ed7872838b40e56a868fb4c7da7da606e9; version=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <46c3b8191aad3d032776bf3bebf03efdf5f4b905; version=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <6428634f7a0b7878144b4925c37856bef3224967; version=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <80600b5d0f3ecb9324120dc95b5e915130f516c5; version=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <b0d0eb13a0441a8ebf4f227843deaf494f1e2c33; version=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <b2c70dd3326809429b709a9c7e9220d29923051a; version=c0b220cf7d80eb8a36ae9f12cae6df4577a6814e <d08d019f2f43a6f9a71e81868bbc326b3afaf37b

Published CVSS scores

5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.3Red HatCVSS:3.1/AV:A/AC:H/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

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

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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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499Endpoint Denial of Service

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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