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.
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History
Tue, 29 Sep 2026 13:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | PyPy pyexpat ExternalEntityParserCreate Use-After-Free | |
| Weaknesses | CWE-416 | |
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| Metrics |
cvssV3_1
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MITRE
Status: PUBLISHED
Assigner: VulnCheck
Published:
Updated: 2026-09-29T12:45:19.797Z
Reserved: 2026-08-19T21:47:08.936Z
Link: CVE-2026-76875
Vulnrichment
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NVD
Status : Received
Published: 2026-09-29T13:17:52.280
Modified: 2026-09-29T13:17:52.280
Link: CVE-2026-76875
Redhat
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Weaknesses