CVE-2026-76875
PyPy pyexpat ExternalEntityParserCreate Use-After-Free
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
6.3
PyPy pyexpat ExternalEntityParserCreate Use-After-Free
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.
- Record
CVE-2026-76875- 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 - 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 - Weakness
- CWE-416
- Updated
- 2026-11-02
EUVDEUVD-2026-88811
6.3
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.
- Record
EUVD-2026-88811- 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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-4h3r-h8c5-46cf
6.3
PyPy before versions 3.11.16 and 3.12.14 contains a use-after-free vulnerability in the pyexpat...
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.
- Record
GHSA-4h3r-h8c5-46cf- 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - 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 - Weakness
- CWE-416
- Updated
- 2026-11-02
NVD
6.3
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.
- Record
CVE-2026-76875- 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - 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 - Weakness
- CWE-416
- Updated
- 2026-11-02
OSV
6.3
PyPy pyexpat ExternalEntityParserCreate Use-After-Free
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.
- Record
CVE-2026-76875- 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 - Weakness
- CWE-416
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-76875
6.3
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.
- Record
DEBIAN-CVE-2026-76875- 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-76875
6.3
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.
- Record
UBUNTU-CVE-2026-76875- 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 - 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 - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
pypy3Debian:12 |
All versions, plus listed versions 7.3.11+dfsg-27.3.11+dfsg-2+deb12u17.3.11+dfsg-2+deb12u27.3.11+dfsg-2+deb12u37.3.12+dfsg-1 Show 26 moreShow less7.3.12~rc1+dfsg-17.3.12~rc2+dfsg-17.3.13+dfsg-17.3.14+dfsg-17.3.15+dfsg-17.3.16+dfsg-17.3.16+dfsg-27.3.17+dfsg-17.3.17+dfsg-27.3.17+dfsg-37.3.18+dfsg-17.3.18+dfsg-27.3.19+dfsg-17.3.19+dfsg-27.3.20+dfsg-17.3.20+dfsg-27.3.20+dfsg-37.3.20+dfsg-47.3.21+dfsg-17.3.21+dfsg-27.3.21+dfsg-37.3.21+dfsg-47.3.22+dfsg-17.3.23+dfsg-17.3.23+dfsg-28.0.0+dfsg-1 |
None known |
pypy3Debian:13 |
All versions, plus listed versions 7.3.19+dfsg-27.3.20+dfsg-17.3.20+dfsg-27.3.20+dfsg-37.3.20+dfsg-4 Show 8 moreShow less7.3.21+dfsg-17.3.21+dfsg-27.3.21+dfsg-37.3.21+dfsg-47.3.22+dfsg-17.3.23+dfsg-17.3.23+dfsg-28.0.0+dfsg-1 |
None known |
pypy3Debian:14 |
before 8.0.0+dfsg-1, plus listed versions 7.3.19+dfsg-27.3.20+dfsg-17.3.20+dfsg-27.3.20+dfsg-37.3.20+dfsg-4 Show 7 moreShow less7.3.21+dfsg-17.3.21+dfsg-27.3.21+dfsg-37.3.21+dfsg-47.3.22+dfsg-17.3.23+dfsg-17.3.23+dfsg-2 |
8.0.0+dfsg-1 |
pypy3Ubuntu:20.04:LTS |
All versions, plus listed versions 7.1.1+dfsg-17.2.0+dfsg-17.3.0+dfsg-17.3.0+dfsg-1ubuntu27.3.0+dfsg-1ubuntu37.3.1+dfsg-47.3.1+dfsg-4ubuntu0.1 |
None known |
pypy3Ubuntu:22.04:LTS |
All versions, plus listed versions 7.3.5+dfsg-27.3.7+dfsg-17.3.7+dfsg-47.3.7+dfsg-57.3.8+dfsg-27.3.9+dfsg-17.3.9+dfsg-1ubuntu0.1 |
None known |
pypy3Ubuntu:24.04:LTS |
All versions, plus listed versions 7.3.12+dfsg-17.3.13+dfsg-17.3.14+dfsg-17.3.15+dfsg-17.3.15+dfsg-1build27.3.15+dfsg-1build3 |
None known |
pypy3Ubuntu:26.10 |
All versions, plus listed versions 7.3.20+dfsg-47.3.23+dfsg-1ubuntu1 |
None known |
pypy3Ubuntu:26.04:LTS |
All versions, plus listed versions 7.3.20+dfsg-37.3.20+dfsg-4 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-76875 is a medium vulnerability (CVSS 6.3) in Pypy, published September 29, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.24%, the 15th percentile. Fixed in pypy3 8.0.0+dfsg-1.
References
doc.pypy.org/release-v8.0.0.html
github.com/pypy/pypy/releases/tag/release-pypy3.12-v8.0.0
github.com/pypy/pypy/releases/tag/release-pypy3.11-v8.0.0
vulncheck.com/advisories/pypy-pyexpat-externalentityparsercreate-use-after-free
nvd.nist.gov/vuln/detail/CVE-2026-76875
github.com/advisories/GHSA-4h3r-h8c5-46cf