# CVE-2026-3276: Potential DoS via quadratic complexity in unicodedata.normalize() > Attackers can cause denial of service by sending crafted Unicode input to unicodedata.normalize(), consuming excessive CPU resources. - **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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:** 3 Jun 2026 - **Updated:** 13 Aug 2026 - **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, CLSA-2026-1786497454, CLSA-2026-1786764414, DEBIAN-CVE-2026-3276, ECHO-3bd2-a10b-bc48, GHSA-jg6j-874m-wgjj, MINI-67v5-5v24-jh8c, MINI-9v2v-xjjc-6jgv, MINI-hx78-vpm4-v27v, MINI-jvq7-3xx7-f62p, MINI-pfv8-h995-8369, PSF-2026-25, ROOT-OS-DEBIAN-11-CVE-2026-3276, SUSE-SU-2026:3655-1, UBUNTU-CVE-2026-3276 ## 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 (Inefficient Algorithmic Complexity) ## Which versions are affected by CVE-2026-3276? 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 | | `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. ## Is CVE-2026-3276 being exploited? There is no known exploitation of CVE-2026-3276 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text 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) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3276 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3276 - OSV: https://osv.dev/vulnerability/CVE-2026-3276 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-3276/ Summaries are generated and may contain mistakes; the official description above is the record.