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.

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact Low

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact Low

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploitation none

Automatable yes

Technical Impact partial

Affected Vendors & Products

Vendors Products
Pypy
  • Pypy

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References
Link Providers
https://doc.pypy.org/release-v8.0.0.html cve-icon cve-icon
https://github.com/pypy/pypy/releases/tag/release-pypy3.11-v8.0.0 cve-icon cve-icon
https://github.com/pypy/pypy/releases/tag/release-pypy3.12-v8.0.0 cve-icon cve-icon
https://www.vulncheck.com/advisories/pypy-pyexpat-externalentityparsercreate-use-after-free cve-icon cve-icon
History

Fri, 02 Oct 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 29 Sep 2026 17:00:00 +0000

Type Values Removed Values Added
First Time appeared Pypy
Pypy pypy
Vendors & Products Pypy
Pypy pypy

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
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'}

cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N'}
cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published: 2026-09-29T12:45:19.797Z

Updated: 2026-11-08T14:08:53.277Z

Reserved: 2026-08-19T21:47:08.936Z

Link: CVE-2026-76875

cve-icon Vulnrichment

Updated: 2026-10-02T12:07:26.295Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-09-29T13:17:52.280

Modified: 2026-10-02T13:17:55.747

Link: CVE-2026-76875

cve-icon Redhat

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