Summary
cryptography vulnerable to NULL-dereference when loading PKCS7 certificates
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.
The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.
CVE-2023-49083 has a CVSS score of 5.9 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (41.0.6); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2023-49083? CVE-2023-49083 is a medium-severity null pointer dereference vulnerability in cryptography (pip), affecting versions >= 3.1, < 41.0.6. It is fixed in 41.0.6. The application dereferences a null pointer, causing a crash.
- How severe is CVE-2023-49083? CVE-2023-49083 has a CVSS score of 5.9 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of cryptography are affected by CVE-2023-49083? cryptography (pip) versions >= 3.1, < 41.0.6 is affected.
- Is there a fix for CVE-2023-49083? Yes. CVE-2023-49083 is fixed in 41.0.6. Upgrade to this version or later.
- Is CVE-2023-49083 exploitable, and should I be worried? Whether CVE-2023-49083 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2023-49083 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2023-49083? Upgrade
cryptographyto 41.0.6 or later.