CVE-2023-49083: Cryptography Cryptography Vulnerable To NULL-dereference When Vulnerability

MODERATE
Advisory Identifier: GHSA-jfhm-5ghh-2f97
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CVSS 5.9
CWE-476
Published
Advisory Summary

CVE-2023-49083 is a MODERATE (CVSS 5.9) cryptography vulnerable to null-dereference when vulnerability (CWE-476: NULL Pointer Dereference) affecting Cryptography libraries in the PyPI ecosystem. The issue involves cryptography vulnerable to null-dereference when loading pkcs7 certificates. Remediation is available by upgrading affected packages to version 41.0.6.

CVE-2023-49083 at a Glance

CVE Identifier CVE-2023-49083
GHSA Identifier GHSA-jfhm-5ghh-2f97
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-476: NULL Pointer Dereference
Affected Product Cryptography
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.9

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2023-49083

To remediate this vulnerability, upgrade all affected Cryptography dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

cryptography fixed: 41.0.6 
pip install cryptography>=41.0.6
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show cryptography

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2023-49083, inspect your installed packages using pip:

pip show cryptography

Analyze the terminal output to locate any version of Cryptography in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 41.0.6), your application is affected.

Note: The pip show cryptography command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-476: NULL Pointer Dereference, where the product dereferences a pointer that it expects to be valid but is null. In Cryptography, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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: ```python 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.

CVE-2023-49083 Affected Cryptography Versions

1 component(s)
Fixed Versions:
41.0.6
Product / Package Ecosystem Affected Versions Fixed Version
cryptography
pypi/cryptography
PyPI
≥ 3.1
< 41.0.6
41.0.6

References

GitHub Advisory / Wiki ADVISORY
https://github.com/pyca/cryptography/security/advisories/GHSA-jfhm-5ghh-2f97
NVD — CVE-2023-49083 NVD
https://nvd.nist.gov/vuln/detail/CVE-2023-49083
Cryptography Source Repository REPOSITORY
https://github.com/pyca/cryptography/pull/9926
Security Fix Commit FIX COMMIT
https://github.com/pyca/cryptography/commit/f09c261ca10a31fe41b1262306db7f8f1da0e48a
Cryptography Source Repository REPOSITORY
https://github.com/pyca/cryptography
Cryptography Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2023-254.yaml
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2024/10/msg00012.html
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QMNTYMUGFJSDBYBU22FUYBHFRZODRKXV
Cryptography Security Information SECURITY
http://www.openwall.com/lists/oss-security/2023/11/29/2

Frequently Asked Questions

What is CVE-2023-49083?
CVE-2023-49083 is a security vulnerability in Cryptography involving cryptography vulnerable to NULL-dereference when loading PKCS7 certificates under CWE-476: NULL Pointer Dereference.
Which Cryptography versions are affected?
Affected versions include releases prior to 41.0.6 across affected packages: cryptography.
What version fixes CVE-2023-49083?
Upgrading to 41.0.6 (or the latest patched release for your respective branch) resolves the vulnerability.
Is cryptography affected?
Yes, cryptography is affected in releases prior to 41.0.6. Upgrade your dependency to 41.0.6 or later.
What is the CVSS score of CVE-2023-49083?
CVE-2023-49083 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2023-49083?
CVE-2023-49083 is classified under CWE-476: NULL Pointer Dereference (The product dereferences a pointer that it expects to be valid but is NULL.).
How can I check PyPI dependencies for CVE-2023-49083?
Run the dependency tree command: 'pip show cryptography'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-jfhm-5ghh-2f97",
  "modified" : "2025-11-04T16:48:52Z",
  "published" : "2023-11-28T20:46:46Z",
  "aliases" : [ "CVE-2023-49083" ],
  "summary" : "cryptography vulnerable to NULL-dereference when loading PKCS7 certificates",
  "details" : "### Summary\n\nCalling `load_pem_pkcs7_certificates` or `load_der_pkcs7_certificates` could lead to a NULL-pointer dereference and segfault.\n\n### PoC\nHere is a Python code that triggers the issue:\n```python\nfrom cryptography.hazmat.primitives.serialization.pkcs7 import load_der_pkcs7_certificates, load_pem_pkcs7_certificates\n\npem_p7 = b\"\"\"\n-----BEGIN PKCS7-----\nMAsGCSqGSIb3DQEHAg==\n-----END PKCS7-----\n\"\"\"\n\nder_p7 = b\"\\x30\\x0B\\x06\\x09\\x2A\\x86\\x48\\x86\\xF7\\x0D\\x01\\x07\\x02\"\n\nload_pem_pkcs7_certificates(pem_p7)\nload_der_pkcs7_certificates(der_p7)\n```\n\n### Impact\nExploitation 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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "cryptography"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.1"
      }, {
        "fixed" : "41.0.6"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/pyca/cryptography/security/advisories/GHSA-jfhm-5ghh-2f97"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2023-49083"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pyca/cryptography/pull/9926"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pyca/cryptography/commit/f09c261ca10a31fe41b1262306db7f8f1da0e48a"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/pyca/cryptography"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2023-254.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2024/10/msg00012.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QMNTYMUGFJSDBYBU22FUYBHFRZODRKXV"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2023/11/29/2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-476" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-11-28T20:46:46Z",
    "nvd_published_at" : "2023-11-29T19:15:07Z"
  }
}