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.
- 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
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
Which versions are affected by CVE-2026-17084?
3 open source packages ship an affected version, including libpython, python and python-min.
| Package | 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 |
Linux distribution packages (7)
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.
Sources
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 and 12 more.