* [3.14] gh-90949: add Expat API to prevent XML deadly allocations (CVE-2025-59375) (GH-139234)
Expose the XML Expat 2.7.2 mitigation APIs to disallow use of
disproportional amounts of dynamic memory from within an Expat
parser (see CVE-2025-59375 for instance).
The exposed APIs are available on Expat parsers, that is,
parsers created by `xml.parsers.expat.ParserCreate()`, as:
- `parser.SetAllocTrackerActivationThreshold(threshold)`, and
- `parser.SetAllocTrackerMaximumAmplification(max_factor)`.
(cherry picked from commit f04bea44c3)
(cherry picked from commit 68a1778b77)
bf2865f80f