Skip to content

[3.11] gh-90949: expose Expat API to tune exponential expansion protections (GH-139368) (GH-151401) - #155346

Open
StanFromIreland wants to merge 2 commits into
python:3.11from
StanFromIreland:backport-db195e3-3.11
Open

[3.11] gh-90949: expose Expat API to tune exponential expansion protections (GH-139368) (GH-151401)#155346
StanFromIreland wants to merge 2 commits into
python:3.11from
StanFromIreland:backport-db195e3-3.11

Conversation

@StanFromIreland

@StanFromIreland StanFromIreland commented Aug 7, 2026

Copy link
Copy Markdown
Member

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)

… 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 <stan@python.org>
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
@StanFromIreland

Copy link
Copy Markdown
Member Author

The only conflict was in the generated AC.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants