CVE-2026-74901: openssl_encrypt before 1.4.0 Authentication Bypass via AES-CTR Fallback

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-17 · updated 2026-09-01
Weakness: CWE-347

Description

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 products

jahlives openssl_encrypt: before 1.4.0 — fixed in 1.4.0

How to fix

Upgrade to a fixed version: jahlives openssl_encrypt 1.4.0. Check the vendor advisory for mitigations.

References

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

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