Tesseract is an open source OCR engine. From 5.4.0 until 5.5.4, AppendLinePolygon in src/api/pagerenderer.cpp destroys the caller-owned right-to-left Pta accumulator while receiving it by value, leaving line_top_rtl_pts and line_bottom_rtl_pts dangling. On an upright Hebrew or Arabic page at the default PAGE XML level, POLYGONFLAG with a false skewed_flag enters the vulnerable calls, while LEVELFLAG greater than zero provides an alternative gate. The calls repeatedly read and free the stale object, causing a double free and use after free and allowing corrupted coordinates to reach RecalcPolygonline. This issue is fixed in version 5.5.4.