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CVE-2026-64044 Linux CVE debrief

A Linux kernel vulnerability, CVE-2026-64044, was resolved. The issue involves ovpn: respect peer refcount in CMD_NEW_PEER error path. The vulnerability arises from ovpn_nl_peer_new_doit()'s error path calling ovpn_peer_release() directly rather than ovpn_peer_put(), bypassing the kref. This affects TCP but not UDP due to differences in how peers are handled.

Vendor
Linux
Product
Unknown
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-19
Original CVE updated
2026-09-02
Advisory published
2026-07-19
Advisory updated
2026-09-02

Who should care

Linux kernel users and administrators should be aware of this vulnerability. The issue is specific to the ovpn (OpenVPN) part of the Linux kernel and affects how peer references are managed in error conditions.

Technical summary

In the Linux kernel, a vulnerability was found in the handling of peer references in the ovpn (OpenVPN) component. Specifically, in the CMD_NEW_PEER error path, ovpn_nl_peer_new_doit() calls ovpn_peer_release() directly instead of ovpn_peer_put(). This bypasses the kref (kernel reference count) mechanism, potentially leading to use-after-free issues. The impact differs between UDP and TCP due to their different handling of peer references. For TCP, this can lead to a situation where a peer is freed while still referenced by a user-space caller, causing issues when the caller attempts to use the freed memory.

Defensive priority

Medium

Recommended defensive actions

  • Apply the official patch or update to a fixed version of the Linux kernel.
  • Review and monitor OpenVPN configurations and logs for unusual activity.
  • Ensure proper error handling and resource management in related code paths.
  • Perform a thorough review of the system for potential indicators of compromise.
  • Check for any unauthorized changes to system configurations or files.
  • Verify that all necessary security updates and patches are applied.
  • Monitor system logs for suspicious activity related to OpenVPN.

Evidence notes

The CVE record was published on 2026-07-19T16:17:44.690Z and has not been modified since then. The NVD entry is currently Received. The vulnerability was resolved by replacing the direct destructor call with ovpn_peer_put() to correctly defer destruction until the last reference is dropped.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-64044 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-64044

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

  • CVE-2026-64044 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-64044

    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/0c3ef71879c0264de6c42463031d9e057da87840

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/1fef6614673ff0846d30acdeeaf3cf98bb5f6116

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/8298834912d76dbc82c12b6b4ab7590ed2bb8ae5

    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.