GHSL-2025-042: Poppler has Use-After-Free

Summary

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.