CVE-2026-80637Network attack vector

Kernel crash via unaligned SYNPROXY timestamp access

Published Aug 28, 2026 · Updated Aug 28, 2026

Unaligned memory access in Linux kernel SYNPROXY timestamp adjustment allows remote attackers to crash strict-alignment systems. The synproxy_tstamp_adjust() function directly reads and writes 32-bit TCP timestamp fields at potentially unaligned option offsets instead of using alignment-safe helpers. The network path is reachable only when SYNPROXY timestamp adjustment is active; affected accesses can degrade performance or crash strict-alignment architectures.

CVSS severityUnavailable
Unscored
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unaligned memory access in Linux kernel SYNPROXY timestamp adjustment allows remote attackers to crash strict-alignment systems. The synproxy_tstamp_adjust() function directly reads and writes 32-bit TCP timestamp fields at potentially unaligned option offsets instead of using alignment-safe helpers. The network path is reachable only when SYNPROXY timestamp adjustment is active; affected accesses can degrade performance or crash strict-alignment architectures.

The record

CVE
CVE-2026-80637
Published
Aug 28, 2026
Updated
Aug 28, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 28, 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=3.12
  2. Affected versionversion=48b1de4c110a7afa4b85862f6c75af817db26fad <2b8e7aaa38002d8ee2f48d87b1f392eadd8e98c4
  3. Affected versionversion=48b1de4c110a7afa4b85862f6c75af817db26fad <5c9c67cf7a3d16051dfb90e98836f530964dfb8e
  4. Affected versionversion=48b1de4c110a7afa4b85862f6c75af817db26fad <992c20bc8a4aba220c8b95b467d049289778dad6
  5. Affected versionversion=48b1de4c110a7afa4b85862f6c75af817db26fad <ea3d2caa5bfacf5db5c1cad521ca5d9144edd9a7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.12; version=48b1de4c110a7afa4b85862f6c75af817db26fad <2b8e7aaa38002d8ee2f48d87b1f392eadd8e98c4; version=48b1de4c110a7afa4b85862f6c75af817db26fad <5c9c67cf7a3d16051dfb90e98836f530964dfb8e; version=48b1de4c110a7afa4b85862f6c75af817db26fad <992c20bc8a4aba220c8b95b467d049289778dad6; version=48b1de4c110a7afa4b85862f6c75af817db26fad <ea3d2caa5bfacf5db5c1cad521ca5d9144edd9a7

Published CVSS scores

No CVSS assessment is available in this record.

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)
Vectornetwork
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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