DCTStream::getChars in DCTStream.cc in Poppler 20.12.1 has a heap-based buffer overflow via a crafted PDF document. NOTE: later reports indicate that this only affects builds from Poppler git clones in late December 2020, not the 20.12.1 release. In this situation, it should NOT be considered a Poppler vulnerability. However, several third-party Open Source projects directly rely on Poppler git clones made at arbitrary times, and therefore the CVE remains useful to users of those projects
CWE-787 - Out-of-Bounds Write
Out-of-bounds write vulnerability is a memory access bug that allows software to write data past the end or before the beginning of the intended buffer. This may result in the corruption of data, a crash, or arbitrary code execution.