CVE-2026-74901

CRITICAL 9.8

openssl_encrypt before 1.4.0 Authentication Bypass via AES-CTR Fallback

CVSS Score

9.8

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-347
Vendor	jahlives
Product	openssl_encrypt
Published	Aug 17, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Affected Versions

jahlives / openssl_encrypt

0 < 1.4.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/jahlives/openssl_encrypt/security/advisories/GHSA-w4j7-wfgw-r52w vulncheck.com: https://www.vulncheck.com/advisories/openssl-encrypt-before-authentication-bypass-via-aes-ctr-fallback