Description
When decompressing crafted zip files using the bzip/LZMA/Zstandard compressions, Python could use an attacker-controlled size to pre-allocate memory, possibly resulting in memory exhaustion.
References10
- github.com/python/cpython/commit/09a2e7e6678b4f65449e7ad8f112c4…
- github.com/python/cpython/commit/1b424c0178a01e155fd0267dc28a8f…
- github.com/python/cpython/commit/31980e84b9a708424a0a1dfecde3fc…
- github.com/python/cpython/commit/6257029de42ef89b67f3d20137de87…
- github.com/python/cpython/commit/9d167992b59cf5e23c66b9ed742b13…
- github.com/python/cpython/commit/c2bfbcdd1a11690507a10bc0998f95…
- github.com/python/cpython/commit/dcdd406ddbfc4cb29b24c3df17cbab…
- github.com/python/cpython/commit/e2311cfb3dd518f008f312fe0631f4…
- github.com/python/cpython/commit/f507e6946a3194e83e1d7b8ee6e145…
- github.com/python/cpython/commit/f897dbf2f36a5935700b7c2d94d468…
Metrics
- CVSS 4.0
-
2.1
LOW
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 1% percentile: 45 · as of 9 November 2026
- CWE
- CWE-400
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.