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CVE-2026-23391 Linux CVE debrief

A vulnerability has been resolved in the Linux kernel related to netfilter: xt_CT. Templates refer to objects that can go away while packets are sitting in nfqueue. This can cause issues on module removal or timeout policy removal. The use of templates with zone and event cache filter are safe, since this just copies values. However, to prevent potential issues, enqueued packets should be flushed in case the template rule gets removed. This issue can have a significant operational impact if not addressed.

Vendor
Linux
Product
Unknown
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-03-25
Original CVE updated
2026-07-14
Advisory published
2026-03-25
Advisory updated
2026-07-14

Who should care

Users of the Linux kernel who utilize netfilter: xt_CT may be affected by this vulnerability. It is recommended to review the affected versions and apply patches as necessary. Affected operators should assess their platform vulnerability and security teams should prioritize patching.

Technical summary

The Linux kernel vulnerability CVE-2026-23391 is related to the netfilter: xt_CT component. The vulnerability arises from the use of templates that refer to objects that can be removed while packets are enqueued in nfqueue. This can lead to issues when the module is removed or the timeout policy is changed. The vulnerability has been addressed by flushing enqueued packets when the template rule is removed. Affected product context requires defensive impact assessment and source-grounded technical framing.

Defensive priority

High

Recommended defensive actions

  • Review and apply patches for the affected Linux kernel versions.
  • Ensure that the Linux kernel is updated to a version that includes the fix for this vulnerability.
  • Monitor for potential issues related to netfilter: xt_CT and template removal.
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
  • Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
  • Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The CVE record was published on 2026-03-25T11:16:39.707Z and was last modified on 2026-07-14T13:18:32.090Z. The NVD entry is currently Modified. This information is based on the provided source corpus. Further verification is recommended to ensure accuracy.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-03-25T11:16:39.707Z and has not been modified since then.