CVE-2026-64554

Host memory corruption via stale IPv6 fragment pointer

Published Jul 27, 2026 · Updated Jul 27, 2026

Use-after-free in the Linux Kernel bridge netfilter path allows adjacent attackers to corrupt kernel memory with crafted IPv6 frames. The br_ip6_fragment() function retains prevhdr into a cloned skb head across skb_checksum_help(), which reallocates the head and leaves a dangling pointer that ip6_frag_next() writes through. A guest or container on an attached bridge can trigger the deterministic write without host credentials or user interaction, causing host kernel memory corruption or a panic.

CVSS severity8.8
High
EPSS probability0.26%
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 the Linux Kernel bridge netfilter path allows adjacent attackers to corrupt kernel memory with crafted IPv6 frames. The br_ip6_fragment() function retains prevhdr into a cloned skb head across skb_checksum_help(), which reallocates the head and leaves a dangling pointer that ip6_frag_next() writes through. A guest or container on an attached bridge can trigger the deterministic write without host credentials or user interaction, causing host kernel memory corruption or a panic.

The record

CVE
CVE-2026-64554
Published
Jul 27, 2026
Updated
Jul 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
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=764dd163ac922f8683b5bcd3007251ce7b26cd33 <00c06ef8c018493943891a7d0ca82b71b24f3180
  3. Affected versionversion=764dd163ac922f8683b5bcd3007251ce7b26cd33 <1c4f67c89fd27c4df4c70b135c2c59627698b3c0
  4. Affected versionversion=764dd163ac922f8683b5bcd3007251ce7b26cd33 <2731efa6364e47934c96eb69e01ea131e8af8030
  5. Affected versionversion=764dd163ac922f8683b5bcd3007251ce7b26cd33 <4ac981a8b7ce7aec99a52d08f8a8953e8e120067
  6. Affected versionversion=764dd163ac922f8683b5bcd3007251ce7b26cd33 <86f3ce81dd2b4b0aa2c3016c989a943e4b1b643d
  7. Affected versionversion=764dd163ac922f8683b5bcd3007251ce7b26cd33 <8c10778ec674b67a07ea042fcba64270f3f38a5a
  8. Affected versionversion=764dd163ac922f8683b5bcd3007251ce7b26cd33 <c141f69d0a0fb16964dbc293650047e69bda8af7
  9. Affected versionversion=764dd163ac922f8683b5bcd3007251ce7b26cd33 <f2e6596d10783557aeb9668da2a3b4d19deb2001

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.3; version=764dd163ac922f8683b5bcd3007251ce7b26cd33 <00c06ef8c018493943891a7d0ca82b71b24f3180; version=764dd163ac922f8683b5bcd3007251ce7b26cd33 <1c4f67c89fd27c4df4c70b135c2c59627698b3c0; version=764dd163ac922f8683b5bcd3007251ce7b26cd33 <2731efa6364e47934c96eb69e01ea131e8af8030; version=764dd163ac922f8683b5bcd3007251ce7b26cd33 <4ac981a8b7ce7aec99a52d08f8a8953e8e120067; version=764dd163ac922f8683b5bcd3007251ce7b26cd33 <86f3ce81dd2b4b0aa2c3016c989a943e4b1b643d; version=764dd163ac922f8683b5bcd3007251ce7b26cd33 <8c10778ec674b67a07ea042fcba64270f3f38a5a; version=764dd163ac922f8683b5bcd3007251ce7b26cd33 <c141f69d0a0fb16964dbc293650047e69bda8af7; version=764dd163ac922f8683b5bcd3007251ce7b26cd33 <f2e6596d10783557aeb9668da2a3b4d19deb2001

Published CVSS scores

8.8kernel.orgCVSS:3.1/AV:A/AC:L/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.

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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

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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