id: PYSEC-2026-1595
published: "2026-07-07T11:45:31.910766Z"
modified: "2026-07-07T17:24:36.761903Z"
aliases:
- CVE-2023-50781
- GHSA-944j-8ch6-rf6x
summary: "m2crypto Bleichenbacher timing attack - incomplete fix for CVE-2020-25657"
details: A flaw was found in m2crypto. This issue may allow a remote attacker to decrypt captured messages in TLS servers that use RSA key exchanges, which may lead to exposure of confidential or sensitive data.
affected:
- package:
    name: m2crypto
    ecosystem: PyPI
    purl: pkg:pypi/m2crypto
  ranges:
  - type: ECOSYSTEM
    events:
    - introduced: "0"
    - last_affected: 0.40.1
  versions:
  - "0.11"
  - "0.13"
  - "0.15"
  - "0.16"
  - "0.17"
  - "0.18"
  - 0.18.1
  - 0.18.2
  - "0.19"
  - 0.19.1
  - "0.20"
  - 0.20.1
  - 0.20.2
  - 0.20beta1
  - "0.21"
  - 0.21.1
  - 0.22.3
  - 0.22.4
  - 0.22.5
  - 0.23.0
  - 0.24.0
  - 0.25.0
  - 0.25.1
  - 0.26.0
  - 0.26.2
  - 0.26.3
  - 0.26.4
  - 0.27.0
  - 0.28.0
  - 0.28.1
  - 0.28.2
  - 0.29.0
  - 0.30.0
  - 0.30.1
  - 0.31.0
  - 0.32.0
  - 0.33.0
  - 0.34.0
  - 0.35.0
  - 0.35.1
  - 0.35.2
  - 0.36.0
  - 0.37.0
  - 0.37.1
  - 0.38.0
  - 0.39.0
  - 0.40.0
  - 0.40.1
references:
- type: ADVISORY
  url: https://nvd.nist.gov/vuln/detail/CVE-2023-50781
- type: WEB
  url: https://access.redhat.com/security/cve/CVE-2023-50781
- type: WEB
  url: https://bugzilla.redhat.com/show_bug.cgi?id=2254426
- type: PACKAGE
  url: https://gitlab.com/m2crypto/m2crypto
- type: WEB
  url: https://gitlab.com/m2crypto/m2crypto/-/issues/342
- type: PACKAGE
  url: https://pypi.org/project/m2crypto
- type: ADVISORY
  url: https://github.com/advisories/GHSA-944j-8ch6-rf6x
severity:
- type: CVSS_V3
  score: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N