CVE-2026-3276 Potential DoS via quadratic complexity in unicodedata.normalize()
Medium 6.3
Published
Updated
Check this codebase for CVE-2026-3276 and fix it if it is affected.
What it is: CVE-2026-3276 is a medium-severity denial of service vulnerability in CPython, published on 3 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-2026-3276 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-2026-3276/ (Markdown: https://insights.sbomify.com/CVE-2026-3276/index.md)
Attackers can cause denial of service by sending crafted Unicode input to unicodedata.normalize(), consuming excessive CPU resources.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-3276?
CVE-2026-3276 is a medium-severity denial of service vulnerability in CPython, published on 3 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
unicodedata.normalize() can take excessive CPU time when processing specially crafted Unicode input containing long runs of combining characters with alternating Canonical Combining Class values. This affects all normalization forms.
Weakness: CWE-407
Which versions are affected by CVE-2026-3276?
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 |
Linux distribution packages (26)
python311 SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | All versions | 3.11.15-150400.9.97.1 |
python311-core SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | All versions | 3.11.15-150400.9.97.1 |
python311-documentation SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | All versions | 3.11.15-150400.9.97.1 |
python311 SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | All versions | 3.11.15-150400.9.97.1 |
python311-core SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | All versions | 3.11.15-150400.9.97.1 |
python311-documentation SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | All versions | 3.11.15-150400.9.97.1 |
python311 SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | All versions | 3.11.15-150400.9.97.1 |
python311-core SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | All versions | 3.11.15-150400.9.97.1 |
python311-documentation SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | All versions | 3.11.15-150400.9.97.1 |
python311 SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | All versions | 3.11.15-150400.9.97.1 |
python311-core SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | All versions | 3.11.15-150400.9.97.1 |
python311-documentation SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | All versions | 3.11.15-150400.9.97.1 |
python311 SUSE:Linux Enterprise Module for Public Cloud 15 SP4 | All versions | 3.11.15-150400.9.97.1 |
python311-core SUSE:Linux Enterprise Module for Public Cloud 15 SP4 | All versions | 3.11.15-150400.9.97.1 |
python311 SUSE:Linux Enterprise Server 15 SP4-LTSS | All versions | 3.11.15-150400.9.97.1 |
python311-core SUSE:Linux Enterprise Server 15 SP4-LTSS | All versions | 3.11.15-150400.9.97.1 |
python311-documentation SUSE:Linux Enterprise Server 15 SP4-LTSS | All versions | 3.11.15-150400.9.97.1 |
python311 SUSE:Linux Enterprise Server 15 SP5-LTSS | All versions | 3.11.15-150400.9.97.1 |
python311-core SUSE:Linux Enterprise Server 15 SP5-LTSS | All versions | 3.11.15-150400.9.97.1 |
python311-documentation SUSE:Linux Enterprise Server 15 SP5-LTSS | All versions | 3.11.15-150400.9.97.1 |
python311 SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | All versions | 3.11.15-150400.9.97.1 |
python311-core SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | All versions | 3.11.15-150400.9.97.1 |
python311-documentation SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | All versions | 3.11.15-150400.9.97.1 |
python311 SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | All versions | 3.11.15-150400.9.97.1 |
python311-core SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | All versions | 3.11.15-150400.9.97.1 |
python311-documentation SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | All versions | 3.11.15-150400.9.97.1 |
How do I fix CVE-2026-3276?
Upgrade libpython to a fixed version for your release line: 3.10.21, 3.11.16, 3.12.14 or 3.13.14.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-3276 being exploited?
There is no known exploitation of CVE-2026-3276 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-3276, AZL-89466, BELL-CVE-2026-3276, BIT-libpython-2026-3276, BIT-python-2026-3276, BIT-python-min-2026-3276 and 14 more.