CVE-2026-6100
Publication date 13 April 2026
Last updated 16 April 2026
Ubuntu priority
Description
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. 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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| pypy3 | 25.10 questing |
Needs evaluation
|
| 24.04 LTS noble |
Needs evaluation
|
|
| 22.04 LTS jammy |
Needs evaluation
|
|
| 20.04 LTS focal |
Needs evaluation
|
|
| python2.7 | 25.10 questing | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Needs evaluation
|
|
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
|
| 16.04 LTS xenial |
Needs evaluation
|
|
| 14.04 LTS trusty |
Needs evaluation
|
|
| python3.4 | 25.10 questing | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 14.04 LTS trusty |
Needs evaluation
|
|
| python3.5 | 25.10 questing | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 16.04 LTS xenial |
Needs evaluation
|
|
| 14.04 LTS trusty |
Needs evaluation
|
|
| python3.6 | 25.10 questing | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 18.04 LTS bionic |
Needs evaluation
|
|
| python3.7 | 25.10 questing | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 18.04 LTS bionic |
Needs evaluation
|
|
| python3.8 | 25.10 questing | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
|
| python3.9 | 25.10 questing | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Needs evaluation
|
|
| python3.10 | 25.10 questing | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Needs evaluation
|
|
| python3.11 | 25.10 questing | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Needs evaluation
|
|
| python3.12 | 25.10 questing | Not in release |
| 24.04 LTS noble |
Needs evaluation
|
|
| 22.04 LTS jammy | Not in release | |
| python3.13 | 25.10 questing |
Needs evaluation
|
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| python3.14 | 25.10 questing |
Needs evaluation
|
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release |
References
Other references
- https://www.cve.org/CVERecord?id=CVE-2026-6100
- https://mail.python.org/archives/list/security-announce@python.org/thread/HTWB2Z6KT5QQX4RYEZAFININDHNOSIF3/
- https://github.com/python/cpython/issues/148395
- https://github.com/python/cpython/pull/148396
- https://github.com/python/cpython/commit/47128e64f98c3a20271138a98c2922bea2a3ee0e
- https://github.com/python/cpython/commit/6a5f79c8d7bbf22b083b240910c7a8781a59437d
- https://github.com/python/cpython/commit/8fc66aef6d7b3ae58f43f5c66f9366cc8cbbfcd2
- https://github.com/python/cpython/commit/c3cf71c3366fe49acb776a639405c0eea6169c20
- https://github.com/python/cpython/commit/e20c6c9667c99ecaab96e1a2b3767082841ffc8b
- http://www.openwall.com/lists/oss-security/2026/04/13/10