CVE-2026-0865 wsgiref.headers.Headers allows header newline injection
Medium 5.9
Published
Updated
Check this codebase for CVE-2026-0865 and fix it if it is affected.
What it is: CVE-2026-0865 is a medium-severity vulnerability in CPython, published on 20 Jan 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-0865 in the wild and no public exploit code.
Affected packages and fixed versions:
- libpython (Bitnami): affected all versions; fixed in 3.10.20, 3.11.15, 3.12.13, 3.13.12, 3.14.3
- python (Bitnami): affected all versions; fixed in 3.10.20, 3.11.15, 3.12.13, 3.13.12, 3.14.3
- python-min (Bitnami): affected all versions; fixed in 3.10.20, 3.11.15, 3.12.13, 3.13.12, 3.14.3
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-2026-0865/ (Markdown: https://insights.sbomify.com/CVE-2026-0865/index.md)
Attackers can inject HTTP headers via newline characters in user-controlled header names or values within the Python wsgiref library.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-0865?
CVE-2026-0865 is a medium-severity vulnerability in CPython, published on 20 Jan 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
User-controlled header names and values containing newlines can allow injecting HTTP headers.
Weakness: CWE-74
Which versions are affected by CVE-2026-0865?
3 open source packages ship an affected version, including libpython, python and python-min.
| Package | Affected | Fixed in |
|---|---|---|
libpython Bitnami | All versions | 3.10.20, 3.11.15, 3.12.13, 3.13.12, 3.14.3 |
python Bitnami | All versions | 3.10.20, 3.11.15, 3.12.13, 3.13.12, 3.14.3 |
python-min Bitnami | All versions | 3.10.20, 3.11.15, 3.12.13, 3.13.12, 3.14.3 |
Linux distribution packages (37)
python-unversioned-command Red Hat:enterprise_linux:9::appstream | All versions | 0:3.9.25-5.el9_8 |
python3-devel Red Hat:enterprise_linux:9::appstream | All versions | 0:3.9.25-5.el9_8 |
python3-tkinter Red Hat:enterprise_linux:9::appstream | All versions | 0:3.9.25-5.el9_8 |
python3.11 Red Hat:enterprise_linux:9::appstream | All versions | 0:3.11.13-7.el9_8 |
python3.11-debuginfo Red Hat:enterprise_linux:9::appstream | All versions | 0:3.11.13-7.el9_8 |
python3.11-debugsource Red Hat:enterprise_linux:9::appstream | All versions | 0:3.11.13-7.el9_8 |
python3.11-devel Red Hat:enterprise_linux:9::appstream | All versions | 0:3.11.13-7.el9_8 |
python3.11-libs Red Hat:enterprise_linux:9::appstream | All versions | 0:3.11.13-7.el9_8 |
python3.11-tkinter Red Hat:enterprise_linux:9::appstream | All versions | 0:3.11.13-7.el9_8 |
python3.12 Red Hat:enterprise_linux:9::appstream | All versions | 0:3.12.12-6.el9_8 |
python3.12-debuginfo Red Hat:enterprise_linux:9::appstream | All versions | 0:3.12.12-6.el9_8 |
python3.12-debugsource Red Hat:enterprise_linux:9::appstream | All versions | 0:3.12.12-6.el9_8 |
python3.12-devel Red Hat:enterprise_linux:9::appstream | All versions | 0:3.12.12-6.el9_8 |
python3.12-libs Red Hat:enterprise_linux:9::appstream | All versions | 0:3.12.12-6.el9_8 |
python3.12-tkinter Red Hat:enterprise_linux:9::appstream | All versions | 0:3.12.12-6.el9_8 |
python3.9-debuginfo Red Hat:enterprise_linux:9::appstream | All versions | 0:3.9.25-5.el9_8 |
python3.9-debugsource Red Hat:enterprise_linux:9::appstream | All versions | 0:3.9.25-5.el9_8 |
python3 Red Hat:enterprise_linux:9::baseos | All versions | 0:3.9.25-5.el9_8 |
python3-libs Red Hat:enterprise_linux:9::baseos | All versions | 0:3.9.25-5.el9_8 |
python3.9 Red Hat:enterprise_linux:9::baseos | All versions | 0:3.9.25-5.el9_8 |
python3.9-debuginfo Red Hat:enterprise_linux:9::baseos | All versions | 0:3.9.25-5.el9_8 |
python3.9-debugsource Red Hat:enterprise_linux:9::baseos | All versions | 0:3.9.25-5.el9_8 |
python3 Red Hat:enterprise_linux:9::crb | All versions | 0:3.9.25-5.el9_8 |
python3-debug Red Hat:enterprise_linux:9::crb | All versions | 0:3.9.25-5.el9_8 |
python3-idle Red Hat:enterprise_linux:9::crb | All versions | 0:3.9.25-5.el9_8 |
python3-test Red Hat:enterprise_linux:9::crb | All versions | 0:3.9.25-5.el9_8 |
python3-tkinter Red Hat:enterprise_linux:9::crb | All versions | 0:3.9.25-5.el9_8 |
python3.11 Red Hat:enterprise_linux:9::crb | All versions | 0:3.11.13-7.el9_8 |
python3.11-debug Red Hat:enterprise_linux:9::crb | All versions | 0:3.11.13-7.el9_8 |
python3.11-debuginfo Red Hat:enterprise_linux:9::crb | All versions | 0:3.11.13-7.el9_8 |
python3.11-debugsource Red Hat:enterprise_linux:9::crb | All versions | 0:3.11.13-7.el9_8 |
python3.11-idle Red Hat:enterprise_linux:9::crb | All versions | 0:3.11.13-7.el9_8 |
python3.11-test Red Hat:enterprise_linux:9::crb | All versions | 0:3.11.13-7.el9_8 |
python3.11-tkinter Red Hat:enterprise_linux:9::crb | All versions | 0:3.11.13-7.el9_8 |
python3.12 Red Hat:enterprise_linux:9::crb | All versions | 0:3.12.12-6.el9_8 |
python3.12-debug Red Hat:enterprise_linux:9::crb | All versions | 0:3.12.12-6.el9_8 |
python3.12-debuginfo Red Hat:enterprise_linux:9::crb | All versions | 0:3.12.12-6.el9_8 |
How do I fix CVE-2026-0865?
Upgrade libpython to a fixed version for your release line: 3.10.20, 3.11.15, 3.12.13 or 3.13.12.
Is CVE-2026-0865 being exploited?
There is no known exploitation of CVE-2026-0865 in the wild and no public exploit code.
Sources
Also known as AZL-75032, AZL-75053, AZL-84272, BELL-CVE-2026-0865, BIT-libpython-2026-0865, BIT-python-2026-0865 and 13 more.