The vulnerability is an insecure deserialization flaw in the BackgroundAugmenter class of imgaug 0.4.0. It leverages Python's pickle module to deserialize data from a multiprocessing queue without validation, allowing an attacker who controls the queue payload to execute arbitrary code within the worker process. This can lead to local or remote code execution depending on how the application is deployed.

The issue affects the imgaug library up to and including version 0.4.0. Any project that imports imgaug and uses the BackgroundAugmenter component is susceptible. The flaw resides in the multicore.py module and is present in all builds that include this code.

Because the deserialization occurs in a background worker, an attacker must supply malicious data to the multiprocessing queue. This could be done through social engineering, executing a compromised script, or tampering with a shared queue in a shared environment. While no public exploit has been observed, the lack of input validation makes this a high‑risk vector, the CVSS score of 9.8 reflects critical severity, and the vulnerability is not listed in CISA KEV. The EPSS score is < 1%, indicating a very low but nonzero exploitation probability.