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GeezerVison is showing github.com — [3.11] gh-90949: expose Expat API to tune exponential expansion protections (GH-139368) (GH-151401) by StanFromIreland · Pull Request #155346 · python/cpython

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@StanFromIreland

@StanFromIreland StanFromIreland commented Aug 7, 2026 •
edited by bedevere-app Bot
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Expose the XML Expat 2.7.2 APIs to tune protections against "billion laughs" [1] attacks.

The exposed APIs are available on Expat parsers, that is, parsers created by xml.parsers.expat.ParserCreate(), as:

  • parser.SetBillionLaughsAttackProtectionActivationThreshold(threshold), and
  • parser.SetBillionLaughsAttackProtectionMaximumAmplification(max_factor).

This completes the work in f04bea4, and improves the existing related documentation.

[1]: https://en.wikipedia.org/wiki/Billion_laughs_attack (cherry picked from commit 6661123) (cherry picked from commit 19bc391) (cherry picked from commit db195e3)

  • Issue: Expose Expat XML attack protection APIs #90949

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@StanFromIreland @picnixz
[3.11] pythongh-90949: expose Expat API to tune exponential expansion…
17b0b06 
… protections (pythonGH-139368) (pythonGH-151401)

Expose the XML Expat 2.7.2 APIs to tune protections against
"billion laughs" [1] attacks.

The exposed APIs are available on Expat parsers, that is,
parsers created by `xml.parsers.expat.ParserCreate()`, as:

- `parser.SetBillionLaughsAttackProtectionActivationThreshold(threshold)`, and
- `parser.SetBillionLaughsAttackProtectionMaximumAmplification(max_factor)`.

This completes the work in f04bea4,
and improves the existing related documentation.

[1]: https://en.wikipedia.org/wiki/Billion_laughs_attack
(cherry picked from commit 6661123)
(cherry picked from commit 19bc391)
(cherry picked from commit db195e3)

Co-authored-by: Stan Ulbrych <[email protected]>
Co-authored-by: Bénédikt Tran <[email protected]>
@StanFromIreland StanFromIreland assigned pablogsal Aug 7, 2026
This was referenced Aug 7, 2026
Expose Expat XML attack protection APIs #90949
Closed
[3.12] gh-90949: expose Expat API to tune exponential expansion protections (GH-139368) #151401
Merged
@bedevere-app bedevere-app Bot added the awaiting core review label Aug 7, 2026
@StanFromIreland

StanFromIreland commented Aug 7, 2026

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The only conflict was in the generated AC.
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@StanFromIreland
Fix capi member access
bdd44c2
@read-the-docs-community

read-the-docs-community Bot commented Aug 7, 2026 •
edited
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Documentation build overview

📚 cpython-previews | 🛠️ Build #33961346 | 📁 Comparing 17b0b06 against main (82905dd)

  🔍 Preview build  

568 files changed · + 18 added · ± 475 modified · - 75 deleted

+ Added

  • c-api/objbuffer.html
  • distutils/_setuptools_disclaimer.html
  • distutils/apiref.html
  • distutils/builtdist.html
  • distutils/commandref.html
  • distutils/configfile.html
  • distutils/examples.html
  • distutils/extending.html
  • distutils/index.html
  • distutils/introduction.html
  • and 8 more...

± Modified

  • about.html
  • bugs.html
  • copyright.html
  • glossary.html
  • index.html
  • license.html
  • py-modindex.html
  • search.html
  • c-api/abstract.html
  • c-api/allocation.html
  • and 465 more...

- Deleted

  • 404.html
  • improve-page-nojs.html
  • improve-page.html
  • _static/tachyon-example-flamegraph.html
  • _static/tachyon-example-heatmap.html
  • c-api/curses.html
  • c-api/extension-modules.html
  • c-api/interp-lifecycle.html
  • c-api/lifecycle.html
  • c-api/monitoring.html
  • and 65 more...
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@pablogsal
pablogsal merged commit 3c1801a into python:3.11 Aug 9, 2026
33 of 37 checks passed

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@bedevere-app bedevere-app Bot removed the awaiting core review label Aug 9, 2026
@StanFromIreland
StanFromIreland deleted the backport-db195e3-3.11 branch August 9, 2026 18:19
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@StanFromIreland @pablogsal
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