CVE-2026-76875

Summary

PyPy before versions 3.11.16 and 3.12.14 contains a use-after-free vulnerability in the pyexpat module's ExternalEntityParserCreate function that allows attackers to corrupt memory by supplying a crafted XML document to applications that create external-entity sub-parsers without retaining a reference to the parent parser. The child parser retains a raw C back-pointer to the parent parser struct while PyPy's tracing garbage collector can free the parent's C struct, causing bundled libexpat to dereference the freed pointer on every parsed token, producing memory corruption.

Affected Software

Weaknesses

• CWE-416: Use After Free

References

• https://doc.pypy.org/release-v8.0.0.html
• https://github.com/pypy/pypy/releases/tag/release-pypy3.12-v8.0.0
• https://github.com/pypy/pypy/releases/tag/release-pypy3.11-v8.0.0
• https://www.vulncheck.com/advisories/pypy-pyexpat-externalentityparsercreate-use-after-free

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