A crafted long short-term memory (LSTM) model file can exploit a boundary check flaw in Tesseract’s WeightMatrix::DeSerializeOld function when compiled with the FAST_FLOAT flag. The function trusts a mode byte from a traineddata file and, upon detecting an unset kDoubleFlag, triggers ASSERT_HOST instead of returning an error. The assert causes the process to abort, so any application that loads the malicious model through TessBaseAPI::Init will terminate, resulting in a denial of service. The weakness is a classic input validation error (CWE‑20) coupled with unsafe procedure routing (CWE‑617).

The vulnerability affects all tesseract‑ocr tesseract releases prior to version 5.5.4. Users running older builds on systems that load custom LSTM models are susceptible if the application passes untrusted files to the OCR engine.

The CVSS score of 5.5 indicates a medium severity, and the EPSS score is currently unavailable. The vulnerability is not listed in the CISA KEV catalog. The attack likely requires an adversary who can supply a crafted model file to an instance of Tesseract, such as via an application that accepts user‑supplied traineddata or by embedding the malicious file into software that uses Tesseract. The exploit results only in service interruption and does not directly compromise confidentiality or integrity, but it can be used to cause disruption in environments where OCR is critical.