Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2026-31678 is a high-severity Time-of-check Time-of-use (TOCTOU) Race Condition (CWE-367) vulnerability in Linux Linux Kernel. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception (T1034); ranked at the 0.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to AC-25 (Reference Monitor) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-31678 is a race condition vulnerability in the Linux kernel's Open vSwitch (Open vSwitch) implementation, specifically in the handling of tunnel network devices. The issue arises in ovs_netdev_tunnel_destroy(), which may execute after NETDEV_UNREGISTER has detached the device, allowing a race where dropping the netdev reference conflicts with concurrent readers still accessing vport->dev. This affects Linux kernel versions incorporating Open vSwitch with tunnel support.
A local attacker with low privileges (PR:L) can exploit this vulnerability with low attack complexity (AC:L) and no user interaction (UI:N), as indicated by its CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H). Successful exploitation could result in high impacts to confidentiality, integrity, and availability, potentially through memory corruption such as use-after-free scenarios during device destruction and reference counting.
Mitigation involves applying the upstream kernel patches provided in the referenced stable commits, which defer the netdev_put operation from ovs_netdev_tunnel_destroy() to an RCU callback in vport_netdev_free(). This aligns the tunnel path with the non-tunnel destroy behavior, eliminating the race without requiring additional RTNL synchronization. Security practitioners should update affected Linux kernels to versions including these fixes: https://git.kernel.org/stable/c/42f0d3d81209654c08ffdde5a34b9b92d2645896, https://git.kernel.org/stable/c/6931d21f87bc6d657f145798fad0bf077b82486c, https://git.kernel.org/stable/c/98b726ab5e2a4811e27c28e4d041f75bba147eab, https://git.kernel.org/stable/c/9d56aced21fb9c104e8a3f3be9b21fbafe448ffc, and https://git.kernel.org/stable/c/b8c56a3fc5d879c0928f207a756b0f067f06c6a8.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-25645
Vulnerability Data
In the Linux kernel, the following vulnerability has been resolved: openvswitch: defer tunnel netdev_put to RCU release ovs_netdev_tunnel_destroy() may run after NETDEV_UNREGISTER already detached the device. Dropping the netdev reference in destroy can race with concurrent readers that still observe…
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vport->dev. Do not release vport->dev in ovs_netdev_tunnel_destroy(). Instead, let vport_netdev_free() drop the reference from the RCU callback, matching the non-tunnel destroy path and avoiding additional synchronization under RTNL.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V15.4.2V17.2.6
Mitigating Controls (NIST 800-53 r5) AI
A reference monitor that is always invoked and analyzable structurally eliminates the non-atomic check-then-use pattern underlying TOCTOU.
Access enforcement that performs an atomic check-and-use decision directly stops the window in which a TOCTOU race can be exploited.
Process isolation limits the blast radius of a successful TOCTOU exploitation but does not remove the race itself.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly include coding standards and reviews that prevent TOCTOU race conditions.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Reliable, synchronized time across systems narrows the exploitable window in which a resource state can change between a security check and its use.