CVE-2026-76875
PyPy pyexpat ExternalEntityParserCreate Use-After-Free
CVSS Score
5.3
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-416 |
| Vendor | pypy |
| Product | pypy |
| Published | Sep 29, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None
Affected Versions
PyPy / PyPy
0 < 3.11.16 3.12.0 < 3.12.14
References
doc.pypy.org: https://doc.pypy.org/release-v8.0.0.html github.com: https://github.com/pypy/pypy/releases/tag/release-pypy3.12-v8.0.0 github.com: https://github.com/pypy/pypy/releases/tag/release-pypy3.11-v8.0.0 vulncheck.com: https://www.vulncheck.com/advisories/pypy-pyexpat-externalentityparsercreate-use-after-free
Credits
Fabian Wahle (Hap Security) VulnCheck