CVE-2026-9669bz2.BZ2Decompressor reuse after error can cause a stack buffer overflow
Updated under an hour ago ()
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It affects Python Software Foundation CPython. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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bz2.BZ2Decompressor objects could be reused after a decompression error. If an application caught the resulting OSError and retried with the same decompressor, crafted input could cause the decompressor to resume from an invalid internal state and perform out-of-bounds writes to a stack buffer. This could crash the process when processing untrusted data.
- CVSS
- 8.2 HIGH (v4.0, CNA)CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- Weakness (CWE)
- CWE-121
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- PSF
- NVD analysis
- Awaiting Analysis
- Record last updated
- Aug 12, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Python Software Foundation CPython python_software_foundation:cpython (from the name) | before 3.10.21; from 3.11.0 before 3.11.16; from 3.12.0 before 3.12.14; from 3.13.0 before 3.13.14; from 3.14.0 before 3.14.6; from 3.15.0a1 before 3.15.0b3 | CNA record |
References
- https://github.com/python/cpython/pull/150600patch
- https://mail.python.org/archives/list/security-announce@python.org/thread/DBJZETMGUIFK7DVUWMOXHD3Z6IX2QPSX/vendor-advisory
- https://github.com/python/cpython/issues/150599issue-tracking
- https://github.com/python/cpython/commit/157a5df8cb5d82b33f918a7489e72ce95ceb12b6patch
- https://github.com/python/cpython/commit/5755d0f083949ff3c5bf3a37e673e24e306b036epatch
- https://github.com/python/cpython/commit/619a12b2e545391dc436b3af79dda22337382a6fpatch
- https://github.com/python/cpython/commit/d3ca26983dfbccdf609f24ff5877dc3118e4702dpatch
- https://github.com/python/cpython/commit/938ec030e90c5e53f1faac6fab1643f14e4f4a79patch
- https://github.com/python/cpython/commit/991e6cf86496718c4ef00b362d640e00cb5c85b2patch
- https://github.com/python/cpython/commit/1ba6135eae75ad8413413caeeedb56ae72320636patch
- http://www.openwall.com/lists/oss-security/2026/06/08/17
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.