CVE-2026-9669

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.

EPSS — Exploit Prediction

0.0038

Probability of exploitation

0.30%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-121 CWE-121

References

Other References

https://github.com/python/cpython/commit/157a5df8cb5d82b33f918a7489e72ce95ceb12b6 https://github.com/python/cpython/commit/5755d0f083949ff3c5bf3a37e673e24e306b036e https://github.com/python/cpython/commit/619a12b2e545391dc436b3af79dda22337382a6f https://github.com/python/cpython/commit/d3ca26983dfbccdf609f24ff5877dc3118e4702d https://github.com/python/cpython/issues/150599 https://github.com/python/cpython/pull/150600 https://mail.python.org/archives/list/[email protected]/thread/DBJZETMGUIFK7DVUWMOXHD3Z6IX2QPSX/ http://www.openwall.com/lists/oss-security/2026/06/08/17

Frequently Asked Questions

What is CVE-2026-9669? +

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.

How do I check if I'm vulnerable to CVE-2026-9669? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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