History

Unreleased

• Added machine-readable attributes to exceptions, allowing UIs to provide more tailored errors.

3.18 (2026-06-02)

• When decoding a domain, add a display argument that will pass through invalid labels rather than raising an exception.

3.17 (2026-05-28)

• Substantial 75% reduction in memory usage through new data structures and some optimization in processing speed.
• Added a general 1024-character input length cap to the public validation, conversion, and codec entry points. This is well above any legitimate domain or label and guards against pathological inputs.

3.16 (2026-05-22)

• Add a command-line interface (python -m idna, also available as the idna script). Encodes or decodes one or more domains supplied as arguments or on standard input, with options to select A-label or U-label output and control error handling.
• Raise the minimum supported Python version to 3.9
• Various code quality improvements

3.15 (2026-05-12)

• Enforce DNS-length cap on individual labels early in check_label, short-circuiting contextual-rule processing for oversized input while staying compatible with UTS 46 usage.
• Tidy core helpers: hoist bidi category sets to module-level frozensets (avoiding per-codepoint list construction), simplify length checks, and reuse the shared _unicode_dots_re from idna.core in the codec module.
• Use raise ... from err for proper exception chaining and switch internal string formatting to f-strings.
• Allow flit_core 4.x in the build backend.
• Expand the ruff lint set (flake8-bugbear, flake8-simplify, pyupgrade, perflint) and apply the surfaced fixes; pin lint CI to Python 3.14.
• Add Dependabot configuration for GitHub Actions.
• Convert README and HISTORY from reStructuredText to Markdown.
• Reference CVE-2026-45409 for the 3.14 advisory in place of the initial GHSA identifier.

Thanks to Felix Yan, Stan Ulbrych, and metsw24-max for contributions to this release.

3.14 (2026-05-10)

• Removed opportunity to process long inputs into quadratic time by rejecting oversize inputs up-front. Closes a bypass of the CVE-2024-3651 mitigation. [CVE-2026-45409]

Thanks to Stan Ulbrych for reporting the issue.

3.13 (2026-04-22)

• Correct classification error for codepoint U+A7F1

3.12 (2026-04-21)

• Update to Unicode 17.0.0.
• Issue a deprecation warning for the transitional argument.
• Added lazy-loading to provide some performance improvements.
• Removed vestiges of code related to Python 2 support, including segmentation of data structures specific to Jython.

Thanks to Rodrigo Nogueira for contributions to this release.

3.11 (2025-10-12)

• Update to Unicode 16.0.0, including significant changes to UTS46 processing. As a result of Unicode ending support for it, transitional processing no longer has an effect and returns the same result.
• Add support for Python 3.14, lowest supported version is Python 3.8.
• Various updates to packaging, including PEP 740 support.

3.10 (2024-09-15)

• Reverted to Unicode 15.1.0 data. Unicode 16 has some significant changes to UTS46 processing that will require more work to properly implement.

3.9 (2024-09-13)

• Update to Unicode 16.0.0
• Deprecate setup.cfg in favour of pyproject.toml
• Use ruff for code formatting

Thanks to Waket Zheng for contributions to this release.

3.8 (2024-08-23)

• Fix regression where IDNAError exception was not being produced for certain inputs.
• Add support for Python 3.13, drop support for Python 3.5 as it is no longer testable.
• Documentation improvements
• Updates to package testing using Github actions

Thanks to Hugo van Kemenade for contributions to this release.

3.7 (2024-04-11)

• Fix issue where specially crafted inputs to encode() could take exceptionally long amount of time to process. [CVE-2024-3651]

Thanks to Guido Vranken for reporting the issue.

3.6 (2023-11-25)

• Fix regression to include tests in source distribution.

3.5 (2023-11-24)

• Update to Unicode 15.1.0
• String codec name is now “idna2008” as overriding the system codec “idna” was not working.
• Fix typing error for codec encoding
• “setup.cfg” has been added for this release due to some downstream lack of adherence to PEP 517. Should be removed in a future release so please prepare accordingly.
• Removed reliance on a symlink for the “idna-data” tool to comport with PEP 517 and the Python Packaging User Guide for sdist archives.
• Added security reporting protocol for project

Thanks Jon Ribbens, Diogo Teles Sant'Anna, Wu Tingfeng for contributions to this release.

3.4 (2022-09-14)

• Update to Unicode 15.0.0
• Migrate to pyproject.toml for build information (PEP 621)
• Correct another instance where generic exception was raised instead of IDNAError for malformed input
• Source distribution uses zeroized file ownership for improved reproducibility

Thanks to Seth Michael Larson for contributions to this release.

3.3 (2021-10-13)

• Update to Unicode 14.0.0
• Update to in-line type annotations
• Throw IDNAError exception correctly for some malformed input
• Advertise support for Python 3.10
• Improve testing regime on Github
• Fix Russian typo in documentation

Thanks to Jon Defresne, Hugo van Kemenade, Seth Michael Larson, Patrick Ventuzelo and Boris Verhovsky for contributions to this release.

3.2 (2021-05-29)

• Add type hints (Thanks, Seth Michael Larson!)
• Remove support for Python 3.4

3.1 (2021-01-04)

• Ensure license is included in package (Thanks, Julien Schueller)
• No longer mark wheel has universal (Thanks, Matthieu Darbois)
• Test on PowerPC using Travis CI

3.0 (2021-01-01)

• Python 2 is no longer supported (the 2.x branch supports Python 2, use “idna<3” in your requirements file if you need Python 2 support)
• Support for V2 UTS 46 test vectors.

2.10 (2020-06-27)

• Update to Unicode 13.0.0.
• Throws a more specific exception if “xn--” is provided as a label.
• This is expected to be the last version that supports Python 2.

2.9 (2020-02-16)

• Update to Unicode 12.1.0.
• Prohibit A-labels ending with a hyphen (Thanks, Julien Bernard!)
• Future-proofing: Test on Python 3.7 and 3.8, don't immediately fail should Python 4 come along.
• Made BSD 3-clause license clearer

2.8 (2018-12-04)

• Update to Unicode 11.0.0.
• Provide more specific exceptions for some malformed labels.

2.7 (2018-06-10)

• Update to Unicode 10.0.0.
• No longer accepts dot-prefixed domains (e.g. “.example”) as valid. This is to be more conformant with the UTS 46 spec. Users should strip dot prefixes from domains before processing.

2.6 (2017-08-08)

• Allows generation of IDNA and UTS 46 table data for different versions of Unicode, by deriving properties directly from Unicode data.
• Ability to generate RFC 5892/IANA-style table data
• Diagnostic output of IDNA-related Unicode properties and derived calculations for a given codepoint
• Support for idna.version to report version
• Support for idna.idnadata.version and idna.uts46data.version to report Unicode version of underlying IDNA and UTS 46 data respectively.

2.5 (2017-03-07)

• Fix bug with Katakana middle dot context-rule (Thanks, Greg Shikhman.)

2.4 (2017-03-01)

• Restore IDNAError to be a subclass of UnicodeError, as some users of this library are only looking for the latter to catch invalid strings.

2.3 (2017-02-28)

• Fix bugs relating to deriving IDNAError from UnicodeError.
• More memory footprint improvements (Thanks, Alex Gaynor)

2.2 (2016-12-21)

• Made some changes to the UTS 46 data that should allow Jython to get around 64kb Java class limits. (Thanks, John A. Booth and Marcin Płonka.)
• In Python 2.6, skip two tests that rely on data not present in that Python version's unicodedata module.
• Use relative imports to help downstream users.

2.1 (2016-03-20)

• Memory consumption optimizations. The library should consume significantly less memory through smarter data structures being used to represent relevant Unicode properties. Many thanks to Shivaram Lingamneni for this patch.
• Patches to make library work better with Python 2.6. The core library currently works however the unit testing does not. (Thanks, Robert Buchholz)
• Better affix all Unicode codepoint properties to a specific version.

2.0 (2015-05-18)

• Added support for Unicode IDNA Compatibility Processing (aka Unicode Technical Standard #46). Big thanks to Jon Ribbens who contributed this functionality.

1.1 (2015-01-27)

• Use IDNA properties from Unicode 6.3.0. Internet Architecture Board (IAB) issued statement recommending against the use of Unicode 7.0.0 until issues relating to U+08A1 codepoint are resolved. See http://goo.gl/Ed1n0K
• Identify some cases when label would be too longer to be a legal DNS name and raise an exception. (Thanks, Ed Lewis)

1.0 (2014-10-12)

• Update IDNA properties for Unicode 7.0.0.

0.9 (2014-07-18)

• Fix issue with non-UTF-8 environments reading the README file now that it contains non-ASCII. (Thanks, Tom Prince)
• Codec functions are useful, so they are separated into their own module, rather than just existing for compatibility reasons.
• Add LICENSE file.

0.8 (2014-07-09)

• Added MANIFEST.in for correct source distribution compilation.

0.7 (2014-07-09)

• Filled out missing tests for various functions.
• Fix bug in CONTEXTO validation for Greek lower numeral sign (U+0375)
• Fix bug in CONTEXTO validation for Japanese middle dot (U+30FB)
• Improved documentation
• Move designation to Stable

0.6 (2014-04-29)

• Minor improvements to Python 3 support, tests (Thanks, Derek Wilson)

0.5 (2014-02-05)

• Update IDNA properties for Unicode 6.3.0.

0.4 (2014-01-07)

• Fix trove classifier for Python 3. (Thanks, Hynek Schlawack)

0.3 (2013-07-18)

• Ported to Python 3.

0.2 (2013-07-16)

• Improve packaging.
• More conformant, passes all relevant tests in the Unicode TR46 test suite.

0.1 (2013-05-27)

• First proof-of-concept version.