CVE-2026-9669 bz2.BZ2Decompressor reuse after error can cause a stack buffer overflow
Attackers can cause a stack buffer overflow and crash the process by reusing a BZ2Decompressor object after an error with crafted input.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-9669?
CVE-2026-9669 is a high-severity memory corruption vulnerability in CPython, published on 8 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-121
Which versions are affected by CVE-2026-9669?
3 open source packages ship an affected version, including libpython, python and python-min.
| Package | Affected | Fixed in |
|---|---|---|
libpython Bitnami | All versions | 3.10.21, 3.11.16, 3.12.14, 3.13.14, 3.14.6 |
python Bitnami | All versions | 3.10.21, 3.11.16, 3.12.14, 3.13.14, 3.14.6 |
python-min Bitnami | All versions | 3.10.21, 3.11.16, 3.12.14, 3.13.14, 3.14.6 |
How do I fix CVE-2026-9669?
Upgrade libpython to a fixed version for your release line: 3.10.21, 3.11.16, 3.12.14 or 3.13.14.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-9669 being exploited?
There is no known exploitation of CVE-2026-9669 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-9669, AZL-90159, BELL-CVE-2026-9669, BIT-libpython-2026-9669, BIT-python-2026-9669, BIT-python-min-2026-9669 and 22 more.