# CVE-2026-76875: PyPy pyexpat ExternalEntityParserCreate Use-After-Free

Status: published. Published: 2026-09-29. Updated: 2026-11-08.

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.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/pypy/pypy/releases/tag/release-pypy3.12-v8.0.0
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/pypy/pypy/releases/tag/release-pypy3.11-v8.0.0

## Affected products and versions

- PyPy / PyPy (pypy/pypy): ≥ 0; < 3.11.16 (affected, semver); ≥ 3.12.0; < 3.12.14 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 6.3 (medium); 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; source: CNA: VulnCheck

- CVSS 3.1: 5.3 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: 0.24% as of 2026-11-08; percentile 15.20%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-416

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://doc.pypy.org/release-v8.0.0.html (CNA: VulnCheck; release-notes)

- https://github.com/pypy/pypy/releases/tag/release-pypy3.12-v8.0.0 (CNA: VulnCheck; patch, release-notes)

- https://github.com/pypy/pypy/releases/tag/release-pypy3.11-v8.0.0 (CNA: VulnCheck; patch, release-notes)

- https://www.vulncheck.com/advisories/pypy-pyexpat-externalentityparsercreate-use-after-free (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-76875; retrieved 2026-11-08; source updated 2026-11-08

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-76875; retrieved 2026-11-08; source updated Not reported

Revision: ce749b00722d9515c74e6145ee3df3629a33d35e1c5280dd87532e127e56aeab

Canonical: https://y2.dev/cve/CVE-2026-76875

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