{"schema_version":"1.7.5","id":"PSF-0000-CVE-2026-6100","published":"2026-04-13T17:15:47.606Z","modified":"2026-07-06T16:11:40.817784896Z","aliases":["BIT-libpython-2026-6100","BIT-python-2026-6100","BIT-python-min-2026-6100","CVE-2026-6100","PSF-2026-18"],"details":"Use-after-free (UAF) was possible in the `lzma.LZMADecompressor`, `bz2.BZ2Decompressor`, and `gzip.GzipFile` when a memory allocation fails with a `MemoryError` and the decompression instance is re-used. This scenario can be triggered if the process is under memory pressure. The fix cleans up the dangling pointer in this specific error condition.\n\nThe 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.","affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/python/cpython","events":[{"introduced":"0"},{"fixed":"6a5f79c8d7bbf22b083b240910c7a8781a59437d"},{"fixed":"8fc66aef6d7b3ae58f43f5c66f9366cc8cbbfcd2"},{"fixed":"c3cf71c3366fe49acb776a639405c0eea6169c20"}]}],"versions":["v0.9.8","v0.9.9","v1.0.1","v1.0.2","v1.1","v1.1.1","v1.2","v1.2b1","v1.2b2","v1.2b3","v1.2b4","v1.3","v1.3b1","v1.4","v1.4b1","v1.4b2","v1.4b3","v1.5","v1.5.1","v1.5.2","v1.5.2a1","v1.5.2a2","v1.5.2b1","v1.5.2b2","v1.5.2c1","v1.5a1","v1.5a2","v1.5a3","v1.5a4","v1.5b1","v1.5b2","v1.6a1","v1.6a2","v2.0","v2.0b1","v2.0b2","v2.0c1","v2.1","v2.1a1","v2.1a2","v2.1b1","v2.1b2","v2.1c1","v2.1c2","v2.2a3","v2.3c1","v2.3c2","v2.4","v2.4a1","v2.4a2","v2.4a3","v2.4b1","v2.4b2","v2.4c1","v3.0a1","v3.0a2","v3.0a3","v3.0a4","v3.0a5","v3.0b1","v3.0b2","v3.0b3","v3.0rc1","v3.0rc2","v3.0rc3","v3.1","v3.10.0a1","v3.10.0a7","v3.11.0a3","v3.11.0a4","v3.11.0a5","v3.11.0a6","v3.11.0a7","v3.11.0b1","v3.12.0a1","v3.12.0a2","v3.12.0a3","v3.12.0a4","v3.12.0a5","v3.12.0a6","v3.12.0a7","v3.12.0b1","v3.13.0","v3.13.0a1","v3.13.0a2","v3.13.0a3","v3.13.0a4","v3.13.0a5","v3.13.0a6","v3.13.0b1","v3.13.0b2","v3.13.0b3","v3.13.0b4","v3.13.0rc1","v3.13.0rc2","v3.13.0rc3","v3.13.1","v3.13.10","v3.13.11","v3.13.12","v3.13.13","v3.13.2","v3.13.3","v3.13.4","v3.13.5","v3.13.6","v3.13.7","v3.13.8","v3.14.0","v3.14.0a1","v3.14.0a2","v3.14.0a3","v3.14.0a4","v3.14.0a5","v3.14.0a6","v3.14.0a7","v3.14.0b1","v3.14.0b2","v3.14.0b3","v3.14.0b4","v3.14.0rc1","v3.14.0rc2","v3.14.0rc3","v3.14.1","v3.14.2","v3.14.3","v3.14.4","v3.15.0a1","v3.15.0a2","v3.15.0a3","v3.15.0a4","v3.15.0a5","v3.15.0a6","v3.15.0a7","v3.15.0a8","v3.1a1","v3.1a2","v3.1b1","v3.1rc1","v3.1rc2","v3.2a1","v3.2a2","v3.2a3","v3.2a4","v3.2b1","v3.2b2","v3.2rc1","v3.2rc2","v3.2rc3","v3.3.0a2","v3.3.0a3","v3.3.0a4","v3.3.0b1","v3.3.0b2","v3.3.0rc1","v3.3.0rc2","v3.3.0rc3","v3.4.0a1","v3.4.0a2","v3.4.0a3","v3.4.0a4","v3.4.0b1","v3.4.0b2","v3.4.0b3","v3.5.0a1","v3.5.0a2","v3.5.0a3","v3.5.0a4","v3.5.0b1","v3.6.0a3","v3.6.0b1","v3.7.0a2","v3.9.0a2"],"database_specific":{"source":"https://github.com/psf/advisory-database/blob/main/advisories/python/PSF-0000-CVE-2026-6100.json","vanir_signatures":[{"deprecated":false,"digest":{"function_hash":"84589999674251724155468361044613684778","length":2206},"id":"PSF-0000-CVE-2026-6100-20b48da3","signature_type":"Function","signature_version":"v1","source":"https://github.com/python/cpython/commit/6a5f79c8d7bbf22b083b240910c7a8781a59437d","target":{"file":"Modules/_bz2module.c","function":"decompress"}},{"deprecated":false,"digest":{"function_hash":"274786089459037806290187256381705341170","length":2221},"id":"PSF-0000-CVE-2026-6100-274a173b","signature_type":"Function","signature_version":"v1","source":"https://github.com/python/cpython/commit/8fc66aef6d7b3ae58f43f5c66f9366cc8cbbfcd2","target":{"file":"Modules/_lzmamodule.c","function":"decompress"}},{"deprecated":false,"digest":{"function_hash":"137817026754399672328269279492351081878","length":2174},"id":"PSF-0000-CVE-2026-6100-59ee1e2b","signature_type":"Function","signature_version":"v1","source":"https://github.com/python/cpython/commit/6a5f79c8d7bbf22b083b240910c7a8781a59437d","target":{"file":"Modules/_lzmamodule.c","function":"decompress"}},{"deprecated":false,"digest":{"function_hash":"84589999674251724155468361044613684778","length":2206},"id":"PSF-0000-CVE-2026-6100-643d6667","signature_type":"Function","signature_version":"v1","source":"https://github.com/python/cpython/commit/c3cf71c3366fe49acb776a639405c0eea6169c20","target":{"file":"Modules/_bz2module.c","function":"decompress"}},{"deprecated":false,"digest":{"function_hash":"285947837918045169759164635510724021861","length":2244},"id":"PSF-0000-CVE-2026-6100-86dedb9f","signature_type":"Function","signature_version":"v1","source":"https://github.com/python/cpython/commit/8fc66aef6d7b3ae58f43f5c66f9366cc8cbbfcd2","target":{"file":"Modules/_bz2module.c","function":"decompress"}},{"deprecated":false,"digest":{"function_hash":"137817026754399672328269279492351081878","length":2174},"id":"PSF-0000-CVE-2026-6100-9e46e21d","signature_type":"Function","signature_version":"v1","source":"https://github.com/python/cpython/commit/c3cf71c3366fe49acb776a639405c0eea6169c20","target":{"file":"Modules/_lzmamodule.c","function":"decompress"}},{"deprecated":false,"digest":{"function_hash":"288422572817338439511797407182616984687","length":2277},"id":"PSF-0000-CVE-2026-6100-c16b4d22","signature_type":"Function","signature_version":"v1","source":"https://github.com/python/cpython/commit/8fc66aef6d7b3ae58f43f5c66f9366cc8cbbfcd2","target":{"file":"Modules/zlibmodule.c","function":"decompress"}},{"deprecated":false,"digest":{"function_hash":"197439806431788498051156381226726719416","length":2238},"id":"PSF-0000-CVE-2026-6100-c46813d4","signature_type":"Function","signature_version":"v1","source":"https://github.com/python/cpython/commit/6a5f79c8d7bbf22b083b240910c7a8781a59437d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