cryptography vulnerable to NULL-dereference when loading PKCS7 certificatesGHSA-jfhm-5ghh-2f97
MEDIUMFix: pyca/cryptography#9926GHSA-jfhm-5ghh-2f97 is a medium-severity (CVSS 5.9) NULL Pointer Dereference vulnerability in cryptography. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for cryptography — see the affected versions and patch details below.
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-jfhm-5ghh-2f97.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
cryptographyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Calling load_pem_pkcs7_certificates or load_der_pkcs7_certificates could lead to a NULL-pointer dereference and segfault.
PoC
Here is a Python code that triggers the issue:
from cryptography.hazmat.primitives.serialization.pkcs7 import load_der_pkcs7_certificates, load_pem_pkcs7_certificates
pem_p7 = b"""
-----BEGIN PKCS7-----
MAsGCSqGSIb3DQEHAg==
-----END PKCS7-----
"""
der_p7 = b"\x30\x0B\x06\x09\x2A\x86\x48\x86\xF7\x0D\x01\x07\x02"
load_pem_pkcs7_certificates(pem_p7)
load_der_pkcs7_certificates(der_p7)
Impact
Exploitation of this vulnerability poses a serious risk of Denial of Service (DoS) for any application attempting to deserialize a PKCS7 blob/certificate. The consequences extend to potential disruptions in system availability and stability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | cryptography | ≥ 3.1&&< 41.0.6 | 41.0.6pip install --upgrade 'cryptography==41.0.6' |
Affected Products
cryptographycryptography.ioResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for cryptography, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update cryptography to 41.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jfhm-5ghh-2f97 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability arises when functions like "load_pem_pkcs7_certificates" or "load_der_pkcs7_certificates" are invoked, triggering the issue during the deserialization of PKCS7 blobs or certificates. The moderate rating is based on the fact that the vulnerability can lead to a segmentation fault, posing a risk of…
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for GHSA-jfhm-5ghh-2f97 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Ansible Automation Platform 2.4 for RHEL 8 | automation-controller-0:4.5.5-2.el8ap | RHSA-2024:1640 |
| Red Hat Ansible Automation Platform 2.4 for RHEL 8 | python3x-cryptography-0:42.0.5-1.el8ap | RHSA-2024:3781 |
| Red Hat Enterprise Linux 8 | python3.11-cryptography-0:37.0.2-6.el8 | RHSA-2024:3105 |
| Red Hat Enterprise Linux 8 | python-cryptography-0:3.2.1-8.el8_10 | RHSA-2025:14553 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | python-cryptography-0:3.2.1-4.el8_4.1 | RHSA-2025:13098 |
| Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | python-cryptography-0:3.2.1-5.1.el8_6.1 | RHSA-2025:13104 |
| Red Hat Enterprise Linux 8.8 Extended Update Support | python3.11-cryptography-0:37.0.2-5.el8_8.1 | RHSA-2024:10965 |
| Red Hat Enterprise Linux 8.8 Telecommunications Update Service | python-cryptography-0:3.2.1-6.el8_8 | RHSA-2025:13100 |
Frequently Asked Questions
Is GHSA-jfhm-5ghh-2f97 in your dependencies?
Find it across PyPI, including transitive dependencies.