---
id: CVE-2026-74901
aliases:
  - PYSEC-2026-3773
  - GHSA-w4j7-wfgw-r52w
title: >-
  openssl_encrypt versions before 1.4.0 contain an authentication bypass
  vulnerability in pqc.py where AES-GCM decryption failures trigger …
summary: >-
  openssl_encrypt versions before 1.4.0 contain an authentication bypass
  vulnerability in pqc.py where AES-GCM decryption failures trigger fallback to
  unauthenticated AES-CTR mode. Attackers can modify ciphertext in transit to
  bypass integ…
severity: none
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: '2026-09-02'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/PYSEC-2026-3773'
references:
  - url: >-
      https://github.com/jahlives/openssl_encrypt/security/advisories/GHSA-w4j7-wfgw-r52w
  - url: >-
      https://www.vulncheck.com/advisories/openssl-encrypt-before-authentication-bypass-via-aes-ctr-fallback
tags:
  - osv
  - pip
epss: 0.00405
epssPercentile: 0.319
ingestedAt: '2026-09-02T19:31:25.950Z'
---

## Overview

openssl_encrypt versions before 1.4.0 contain an authentication bypass vulnerability in pqc.py where AES-GCM decryption failures trigger fallback to unauthenticated AES-CTR mode. Attackers can modify ciphertext in transit to bypass integrity verification and perform bit-flipping attacks without detection.

## Affected packages

- `openssl-encrypt < 1.4.0`

## Remediation

Upgrade to a patched release:

- `openssl-encrypt 1.4.0`