# CVE-2026-17084: stringprep.map_table_b2() deviates from RFC 3454 Table B.2 > The Python stringprep module incorrectly processes Unicode characters, causing IDNA domain name mismatches for specific characters. - **Severity:** Medium 6.0 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** A user has to click or open something - **Fix available:** Yes - **Published:** 18 Aug 2026 - **Updated:** 2 Oct 2026 - **Also known as:** ALPINE-CVE-2026-17084, AZL-96870, BELL-CVE-2026-17084, BIT-libpython-2026-17084, BIT-python-2026-17084, BIT-python-min-2026-17084, CLSA-2026-1791403199, DEBIAN-CVE-2026-17084, ECHO-fca2-5d51-7d6d, GHSA-w246-x8qv-r8f5, MINI-22r3-8vpm-rhm7, MINI-gm76-4qxc-mwwv, MINI-pxf4-h5xv-pw74, MINI-vxhp-6rh7-hgr9, MINI-x6cv-hqqw-46m6, PSF-2026-37, RHSA-2026:74868, UBUNTU-CVE-2026-17084 ## What is CVE-2026-17084? CVE-2026-17084 is a medium-severity vulnerability in CPython, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link. ### Official description The "stringprep" module didn't process characters from RFC 3454 tables B.2 or B.3 correctly: the latest Unicode codepoint attributes were used instead of the specified Unicode 3.2.0. This behavior would cause mismatches when processing domain names using IDNA 2003 (the "idna" codec) and the in_table_b2() function of the "stringprep" module. This only affects domain names containing characters that were not previously registered or had their Unicode attributes such as case-folding behavior updated since Unicode 3.2.0. Weakness: CWE-436 (Interpretation Conflict) ## Which versions are affected by CVE-2026-17084? 3 open source packages ship an affected version, including libpython, python and python-min. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `libpython` | Bitnami | All versions | 3.10.22, 3.11.17, 3.12.15, 3.13.16, 3.14.8 | | `python` | Bitnami | All versions | 3.10.22, 3.11.17, 3.12.15, 3.13.16, 3.14.8 | | `python-min` | Bitnami | All versions | 3.10.22, 3.11.17, 3.12.15, 3.13.16, 3.14.8 | | `python3.10` | Red Hat:hummingbird:1 | All versions | 0:3.10.22-1.hum1 | | `python3.10-debug` | Red Hat:hummingbird:1 | All versions | 0:3.10.22-1.hum1 | | `python3.10-devel` | Red Hat:hummingbird:1 | All versions | 0:3.10.22-1.hum1 | | `python3.10-idle` | Red Hat:hummingbird:1 | All versions | 0:3.10.22-1.hum1 | | `python3.10-libs` | Red Hat:hummingbird:1 | All versions | 0:3.10.22-1.hum1 | | `python3.10-test` | Red Hat:hummingbird:1 | All versions | 0:3.10.22-1.hum1 | | `python3.10-tkinter` | Red Hat:hummingbird:1 | All versions | 0:3.10.22-1.hum1 | ## How do I fix CVE-2026-17084? Upgrade libpython to a fixed version for your release line: 3.10.22, 3.11.17, 3.12.15 or 3.13.16. ## Is CVE-2026-17084 being exploited? There is no known exploitation of CVE-2026-17084 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-17084 and fix it if it is affected. What it is: CVE-2026-17084 is a medium-severity vulnerability in CPython, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link. Exploitation: There is no known exploitation of CVE-2026-17084 in the wild and no public exploit code. Affected packages and fixed versions: - libpython (Bitnami): affected all versions; fixed in 3.10.22, 3.11.17, 3.12.15, 3.13.16, 3.14.8 - python (Bitnami): affected all versions; fixed in 3.10.22, 3.11.17, 3.12.15, 3.13.16, 3.14.8 - python-min (Bitnami): affected all versions; fixed in 3.10.22, 3.11.17, 3.12.15, 3.13.16, 3.14.8 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-2026-17084/ (Markdown: https://insights.sbomify.com/CVE-2026-17084/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-17084 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-17084 - OSV: https://osv.dev/vulnerability/CVE-2026-17084 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-17084/ Summaries are generated and may contain mistakes; the official description above is the record.