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CVE-2026-9669
bz2.BZ2Decompressor reuse after error can cause a stack buffer overflow
High8.2EPSS 0.43%
- Published
- Updated
- Reserved
- Assigned by
- PSF
Description
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| PSFCNA (assigner) | 4.0 | High8.2 | 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 |
| NVDNVD · Awaiting Analysis | 4.0 | High8.2 | 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/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 (exploitation in 30 days)
- 0.43% · top 63% of all CVEs (5 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
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The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.2.
Weakness
Affected products
Python Software Foundation · CPython
- affected < 3.10.21
- affected 3.11.0 – < 3.11.16
- affected 3.12.0 – < 3.12.14
- affected 3.13.0 – < 3.13.14
- affected 3.14.0 – < 3.14.6
- affected 3.15.0a1 – < 3.15.0b3
References (11)
- https://github.com/python/cpython/pull/150600 (opens in a new tab)patch
- https://mail.python.org/archives/list/[email protected]/thread/DBJZETMGUIFK7DVUWMOXHD3Z6IX2QPSX/ (opens in a new tab)vendor-advisory
- https://github.com/python/cpython/issues/150599 (opens in a new tab)issue-tracking
- https://github.com/python/cpython/commit/157a5df8cb5d82b33f918a7489e72ce95ceb12b6 (opens in a new tab)patch
- https://github.com/python/cpython/commit/5755d0f083949ff3c5bf3a37e673e24e306b036e (opens in a new tab)patch
- https://github.com/python/cpython/commit/619a12b2e545391dc436b3af79dda22337382a6f (opens in a new tab)patch
- https://github.com/python/cpython/commit/d3ca26983dfbccdf609f24ff5877dc3118e4702d (opens in a new tab)patch
- https://github.com/python/cpython/commit/938ec030e90c5e53f1faac6fab1643f14e4f4a79 (opens in a new tab)patch
- https://github.com/python/cpython/commit/991e6cf86496718c4ef00b362d640e00cb5c85b2 (opens in a new tab)patch
- https://github.com/python/cpython/commit/1ba6135eae75ad8413413caeeedb56ae72320636 (opens in a new tab)patch
- http://www.openwall.com/lists/oss-security/2026/06/08/17 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-9669)Record last updated .