The Linux kernel’s mtd:spi‑nor driver contains a logic error that makes it impossible to unlock only those flash blocks that are currently locked. The unlock path erroneously checks top‑bottom lock flags and miscalculates lock length, causing a failure when the user requests to unlock a subset of locked blocks. This flaw prevents legitimate unblocking of flash sectors while leaving higher‑level system functionality intact. The impact is limited to a device‑level denial of service because the failure affects only the flash locking mechanism. The vulnerability is a direct result of improper input validation and calculation errors.

All Linux kernels that incorporate the mtd:spi‑nor driver and were compiled before the fixed commit 12d4d69221 are affected. This includes the default kernels in any distribution that has not applied the update, as the driver is part of the generic MTD subsystem and its sysfs interface is used by many user‑space utilities.

The CVSS score of 5.5 indicates moderate severity. The EPSS figure of less than 1 % suggests a very low probability of widespread exploitation. The vulnerability is not listed in CISA’s KEV catalog, and there is no known remote code execution path. Exploitation would require local or privileged access to the device’s sysfs interface to issue unlock commands, which limits the threat to environments where such access is granted. Consequently, overall risk is moderate for sensitive deployments and low for general use.