# 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.

- **Severity:** High 8.2 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Jun 2026
- **Updated:** 13 Aug 2026
- **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, CLSA-2026-1789461197, CLSA-2026-1789575335, CLSA-2026-1789578322, CLSA-2026-1789578714, CLSA-2026-1789641197, CLSA-2026-1789661605, CLSA-2026-1789662564, CLSA-2026-1789747235, CLSA-2026-1789748541, DEBIAN-CVE-2026-9669, ECHO-19f0-b298-0f29, GHSA-8jvr-397x-xqh9, MINI-4545-2pqg-6xjm, MINI-824c-w9j2-p6mr, MINI-mv7v-9m9r-xpx9, MINI-r27c-vgmp-9fvq, MINI-v5hm-4gxm-cff8, PSF-2026-27, ROOT-OS-ALPINE-320-CVE-2026-9669, ROOT-OS-DEBIAN-11-CVE-2026-9669, ROOT-OS-DEBIAN-12-CVE-2026-9669, UBUNTU-CVE-2026-9669

## 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 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-9669?

3 open source packages ship an affected version, including libpython, python and python-min.


| Package | Ecosystem | 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.

## Is CVE-2026-9669 being exploited?

There is no known exploitation of CVE-2026-9669 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-9669 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-9669 in the wild and no public exploit code.

Affected packages and fixed versions:
- libpython (Bitnami): affected all versions; fixed in 3.10.21, 3.11.16, 3.12.14, 3.13.14, 3.14.6
- python (Bitnami): affected all versions; fixed in 3.10.21, 3.11.16, 3.12.14, 3.13.14, 3.14.6
- python-min (Bitnami): affected all versions; fixed in 3.10.21, 3.11.16, 3.12.14, 3.13.14, 3.14.6

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-9669/ (Markdown: https://insights.sbomify.com/CVE-2026-9669/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-9669
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-9669
- OSV: https://osv.dev/vulnerability/CVE-2026-9669

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-9669/
Summaries are generated and may contain mistakes; the official description above is the record.