---
id: CVE-2026-74882
aliases:
  - PYSEC-2026-3744
  - GHSA-2592-7m3g-7fq6
title: >-
  openssl_encrypt versions before 1.4.0 contain an insecure default
  configuration that trusts the entire RFC 1918 private address space in …
summary: >-
  openssl_encrypt versions before 1.4.0 contain an insecure default
  configuration that trusts the entire RFC 1918 private address space in
  IntegrityProxyConfig trusted_proxies. Attackers on private networks can forge
  client certificate hea…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'
vendor: openssl-encrypt
product: openssl-encrypt
ecosystem: pip
affected:
  - openssl-encrypt < 1.4.0
patched:
  - openssl-encrypt 1.4.0
published: '2026-08-17'
updated: '2026-09-01'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/PYSEC-2026-3744'
references:
  - url: >-
      https://github.com/jahlives/openssl_encrypt/security/advisories/GHSA-2592-7m3g-7fq6
  - url: >-
      https://www.vulncheck.com/advisories/openssl-encrypt-before-insecure-default-configuration
tags:
  - osv
  - pip
epss: 0.00167
epssPercentile: 0.05261
ingestedAt: '2026-09-02T19:31:24.709Z'
---

## Overview

openssl_encrypt versions before 1.4.0 contain an insecure default configuration that trusts the entire RFC 1918 private address space in IntegrityProxyConfig trusted_proxies. Attackers on private networks can forge client certificate headers to bypass mTLS authentication when ProxyAuth validation is relaxed or modified.

## Affected packages

- `openssl-encrypt < 1.4.0`

## Remediation

Upgrade to a patched release:

- `openssl-encrypt 1.4.0`