Raw vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2025-21746 is a medium-severity Time-of-check Time-of-use (TOCTOU) Race Condition (CWE-367) vulnerability in Linux Linux Kernel. Its CVSS base score is 4.7 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception (T1034); ranked at the 4th 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.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-5183
Vulnerability Data
In the Linux kernel, the following vulnerability has been resolved: Input: synaptics - fix crash when enabling pass-through port When enabling a pass-through port an interrupt might come before psmouse driver binds to the pass-through port. However synaptics sub-driver tries…
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to access psmouse instance presumably associated with the pass-through port to figure out if only 1 byte of response or entire protocol packet needs to be forwarded to the pass-through port and may crash if psmouse instance has not been attached to the port yet. Fix the crash by introducing open() and close() methods for the port and check if the port is open before trying to access psmouse instance. Because psmouse calls serio_open() only after attaching psmouse instance to serio port instance this prevents the potential crash.
- 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.