Poppler ia a library for rendering PDF files, and examining or modifying their structure. A use-after-free (write) vulnerability has been detected in versions Poppler prior to 25.10.0 within the StructTreeRoot class. The issue arises from the use of raw pointers to elements of a std::vector, which can lead to dangling pointers when the vector is resized. The vulnerability stems from the way that refToParentMap stores references to std::vector elements using raw pointers. These pointers may become invalid when the vector is resized. This vulnerability is a common security problem involving the use of raw pointers to std::vectors. Internally, std::vector stores its elements in a dynamically allocated array. When the array reaches its capacity and a new element is added, the vector reallocates a larger block of memory and moves all the existing elements to the new location. At this point if any pointers to elements are stored before a resize occurs, they become dangling pointers once the reallocation happens. Version 25.10.0 contains a patch for the issue.
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.