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PatchSiren cyber security CVE debrief

CVE-2026-64007 Linux CVE debrief

A vulnerability in the Linux kernel has been patched. The vulnerability is related to the netfilter synproxy component. An issue was found with the synproxy_tstamp_adjust function, which could lead to a checksum update being written to the wrong location, resulting in either a write to freed slab memory or a packet being sent with an incorrect checksum. This issue could allow an attacker to cause a denial of service or potentially execute arbitrary code.

Vendor
Linux
Product
Unknown
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-19
Original CVE updated
2026-07-30
Advisory published
2026-07-19
Advisory updated
2026-07-30

Who should care

Users of the Linux kernel should be aware of this vulnerability and take steps to ensure their systems are updated with the latest patches. Operators of Linux-based systems, platform administrators, vulnerability management teams, and security teams should review the vulnerability and assess their exposure.

Technical summary

The synproxy_tstamp_adjust function in the Linux kernel's netfilter component was found to have a vulnerability. The function rewrites the TCP timestamp option in place and then updates the TCP checksum. However, between obtaining the TCP header pointer and using it, the function calls skb_ensure_writable, which can free the old skb->head. This can cause the cached TCP header pointer to become stale, leading to a checksum update being written to the wrong location. The issue affects Linux kernel versions and could be exploited remotely.

Defensive priority

High

Recommended defensive actions

  • Apply the latest Linux kernel patches
  • Ensure systems are updated with the latest security patches
  • Monitor systems for potential exploitation attempts
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-07-19T16:17:40.407Z and has not been modified since then. The NVD entry is currently Received. Evidence is limited to CVE and NVD details. Defenders should verify system patch levels and review vulnerability context with Linux kernel maintainers and other sources for further information.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-64007 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-64007

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

  • CVE-2026-64007 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-64007

    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/92170e6afe927ab2792a3f71902845789c8e31b1

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/9902a1058992de5d95656b64a3bd95c077f7ba2c

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/a91887a5b6ee4b98dfbf1db657ed2b879430149e

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/af2c22ccb1f621aff487ff47a040e38e058541e7

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/c7f945f7da097245a2f8ed7775ce48421047ee96

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/d3019c61799adc21811af4b521f11f3dc77f8e04

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/dd206819f210522579010d889d45a9530bb494bc

    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.