CVE-2026-6100

A flaw was found in Python's decompression modules, including `lzma.LZMADecompressor`, `bz2.BZ2Decompressor`, and `gzip.GzipFile`. This vulnerability, a use-after-free, can occur if a program attempts to re-use a decompression object after a memory allocation error, especially when the system is experiencing high memory usage. Exploitation of this flaw could potentially allow an attacker to execute arbitrary code or access sensitive data. The vulnerability is only present if the program re-uses decompressor instances across multiple decompression calls even after a `MemoryError` is raised during decompression. Using the helper functions to one-shot decompress data such as `lzma.decompress()`, `bz2.decompress()`, `gzip.decompress()`, and `zlib.decompress()` are not affected as a new decompressor instance is used per call. If the decompressor instance is not re-used after an error condition, this usage is similarly not vulnerable.