The fsl_ucc_hdlc driver in the Linux kernel mistakenly calls dma_free_coherent twice on a single contiguous buffer allocated in uhdlc_init, corrupting kernel memory and leading to a kernel panic. This classic denial of service flaw is classified by the CNA as CWE‑1341, indicating improper handling of dynamic memory and assertions.

Affected version information is not available. Any Linux kernel that includes the fsl_ucc_hdlc module without the upstream commit is affected. The vulnerability resides in the net:wan/fsl_ucc_hdlc subsystem, which may be compiled or loaded as a module in various distributions.

Based on the description, it is inferred that a local attacker capable of interacting with the wan/hdlc interface or forcing a module unload could trigger the faulty cleanup and cause a crash. The CVSS score of 5.5 indicates moderate severity, and the EPSS score is <1%, suggesting a low probability of exploitation. The vulnerability is not listed in the CISA KEV catalog, so the exploitation likelihood remains uncertain. The primary impact is loss of availability; no code execution path is documented.