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PatchSiren cyber security CVE debrief

CVE-2026-64016 Linux CVE debrief

A Linux kernel vulnerability was resolved, addressing an issue with ksmbd's durable reconnect error path file lifetime. After a durable reconnect succeeds, ksmbd_reopen_durable_fd() republishes the same ksmbd_file into the session volatile-id table. If smb2_open() then takes a later error path, cleanup first calls ksmbd_fd_put(work, fp) and then unconditionally calls ksmbd_put_durable_fd(dh_info.fp). This can lead to the file object being freed without removing the volatile-id entry that was just published into the session table. The vulnerability has a medium defensive priority, and Linux kernel users and administrators should take steps to ensure their systems are updated with the latest patches.

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

Linux kernel users and administrators, as well as security teams and vulnerability management teams, should be aware of this vulnerability and take steps to ensure their systems are updated with the latest patches. This vulnerability affects Linux kernel deployments, and operators should review their environments for potential exposure.

Technical summary

The vulnerability is related to the ksmbd module in the Linux kernel, specifically dealing with the durable reconnect error path file lifetime. When a durable reconnect succeeds, the same ksmbd_file is republished into the session volatile-id table. However, if an error occurs later, the cleanup process may not properly handle the file object, potentially leading to a use-after-free vulnerability. The technical impact is that an attacker could potentially exploit this vulnerability to gain unauthorized access to sensitive data or disrupt system operations.

Defensive priority

Medium

Recommended defensive actions

  • Apply the latest Linux kernel patches to ensure the vulnerability is addressed.
  • Review and update ksmbd configurations to prevent similar issues in the future.
  • Monitor system logs for any suspicious activity related to ksmbd.
  • 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 2026-07-19T16:17:41.577Z and has not been modified since then. The NVD entry is currently Received. The vulnerability is related to the Linux kernel and specifically deals with the ksmbd module's durable reconnect error path file lifetime. Evidence is limited, and defenders should verify their environments for potential exposure.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-64016 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-64016

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

  • CVE-2026-64016 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-64016

    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/3515503322f4819277091839eed46b695096aca5

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/6cb0b9385320110fe24a5d5ac0000ade4bb3a3f3

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/a1a39f227c80cbf369767badc32cba2b225147d1

    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.