PyPy pyexpat ExternalEntityParserCreate Use-After-Free (CVE-2026-76875) | HOL Guard CVE

Medium · CVSS 6.3CVE-2026-76875

PyPy pyexpat ExternalEntityParserCreate Use-After-Free

Answer in brief

CVE-2026-76875 records a Medium severity (CVSS 6.3) vulnerability in PyPy pyexpat ExternalEntityParserCreate Use-After-Free. The current sources do not mark it as known exploited. The current feed maps PyPy/PyPy (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 29, 2026Updated Sep 29, 2026Source checked Sep 29, 2026First seen by HOL Sep 29, 2026Material review Sep 29, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 6.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 6.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps PyPy/PyPy (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
PyPy/PyPygeneric	>=0 <3.11.16 \|\| >=3.12.0 <3.12.14	3.11.16, 3.12.14

Recommended response

Check inventory. Check lockfiles and deployed manifests for PyPy/PyPy.
Review the reported fix. Update PyPy/PyPy to 3.11.16 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 29, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 29, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 29, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.