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CVE-2026-80637 Linux CVE debrief

The CVE-2026-80637 vulnerability involves an unaligned memory access issue in the Linux kernel's netfilter synproxy component. This issue arises from improper handling of timestamp adjustments, which can lead to performance degradation or crashes on strict alignment architectures. The vulnerability is resolved by using get_unaligned_be32() and put_unaligned_be32() to safely read and write timestamp fields. This fix follows the implementation of timestamp parsing in the networking stack at tcp_parse_options() and synproxy_parse_options(). Linux kernel users, administrators, and security teams should be aware of this vulnerability and assess their exposure. This includes users of Linux-based systems, cloud providers, and organizations relying on Linux infrastructure. The vulnerability has a CVSS score of 7.5 and is considered HIGH severity.

Vendor
Linux
Product
Unknown
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-08-28
Original CVE updated
2026-08-29
Advisory published
2026-08-28
Advisory updated
2026-08-29

Who should care

Linux kernel users, administrators, and security teams should be aware of this vulnerability and assess their exposure. This includes users of Linux-based systems, cloud providers, and organizations relying on Linux infrastructure.

Technical summary

The CVE-2026-80637 vulnerability involves an unaligned memory access issue in the Linux kernel's netfilter synproxy component. The vulnerability is caused by improper handling of timestamp adjustments, which can lead to performance degradation or crashes on strict alignment architectures. The issue is resolved by using get_unaligned_be32() and put_unaligned_be32() to safely read and write timestamp fields.

Defensive priority

This vulnerability has a CVSS score of 7.5 and is considered HIGH severity. Linux kernel users should assess their exposure and apply patches if available.

Recommended defensive actions

  • Inventory Linux systems using the affected kernel versions and assess exposure.
  • Apply patches or updates provided by the Linux kernel maintainers.
  • Monitor network traffic and system logs for potential exploitation attempts.
  • Consider implementing compensating controls, such as network filtering or intrusion detection systems.
  • Review and verify the integrity of affected systems.
  • Track and document changes to the Linux kernel and related components.
  • Implement additional monitoring and logging to detect potential exploitation attempts.

Evidence notes

The CVE-2026-80637 vulnerability involves an unaligned memory access issue in the Linux kernel's netfilter synproxy component. The vulnerability is caused by improper handling of timestamp adjustments, which can lead to performance degradation or crashes on strict alignment architectures. The issue is resolved by using get_unaligned_be32() and put_unaligned_be32() to safely read and write timestamp fields.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-80637 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-80637

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-80637 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-80637

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/2b8e7aaa38002d8ee2f48d87b1f392eadd8e98c4

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/5c9c67cf7a3d16051dfb90e98836f530964dfb8e

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/992c20bc8a4aba220c8b95b467d049289778dad6

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/ea3d2caa5bfacf5db5c1cad521ca5d9144edd9a7

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.