# History

## 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.
