Which versions of openssl_encrypt are affected by EUVD-2026-60118?

The openssl_encrypt Python library (versions before 1.4.0) contains a critical authentication bypass vulnerability that allows attackers to manipulate encrypted data in transit without detection by…. A patch is available.

How to fix or mitigate EUVD-2026-60118?

Within 24 hours, inventory all systems and applications using openssl_encrypt library and prioritize those handling sensitive data or customer information. Within 7 days, deploy openssl_encrypt version 1.4.0 or later across all affected production systems and critical infrastructure. Within 30 days, complete deployment to remaining systems, verify patch installation across your estate, and implement enhanced monitoring for ciphertext manipulation attempts during the vulnerability exposure window.

openssl_encrypt EUVD-2026-60118

Q: What is the CVSS score of EUVD-2026-60118?

EUVD-2026-60118 has a CVSS 4.0 base score of 9.3 (Critical). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.2%.

| CVE-2026-74901 CRITICAL

Improper Verification of Cryptographic Signature (CWE-347)

2026-08-17 VulnCheck

GHSA-jw8h-gwjw-g7rc

Authentication Bypass Jwt Attack Openssl Encrypt Jahlives

9.3

CVSS 4.0 · Vendor: VulnCheck

Severity by source

Vendor (VulnCheck) PRIMARY

9.3 CRITICAL

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

6.5 MEDIUM

Network delivery but requires an active in-transit tampering position (AC:H); core impact is undetected integrity forgery (I:H) with only incidental confidentiality (C:L) and no availability impact.

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

4.0 AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Analysis Generated

Aug 17, 2026 - 13:01 vuln.today

Patch available

Aug 17, 2026 - 12:01 EUVD

CVE Published

Aug 17, 2026 - 11:04 cve.org

CRITICAL 9.3

DescriptionCVE.org

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.

AnalysisAI

Authentication bypass in the openssl_encrypt Python library (versions before 1.4.0) lets attackers who can tamper with ciphertext in transit defeat integrity protection, because a failed AES-GCM authenticated decryption in pqc.py silently falls back to unauthenticated AES-CTR. Reported by VulnCheck and carrying a CVSS 4.0 base score of 9.3, the flaw enables undetected bit-flipping and ciphertext manipulation. No public exploit identified at time of analysis, but a vendor patch is available.

Technical ContextAI

openssl_encrypt is a Python encryption utility/library authored by 'jahlives' (CPE cpe:2.3:a:jahlives:openssl_encrypt). The vulnerable code path is in pqc.py, the module handling post-quantum/hybrid cryptographic operations. Normally AES-GCM provides authenticated encryption (AEAD), so any tampering with the ciphertext or authentication tag causes decryption to fail. The defect is that when AES-GCM authentication fails, the code does not abort - it falls back to AES-CTR, a confidentiality-only mode with no integrity/authentication guarantee. This maps to CWE-347 (Improper Verification of Cryptographic Signature), here the cryptographic integrity tag: modified ciphertext is accepted and decrypted rather than rejected. Because CTR is a stream cipher (keystream XORed with plaintext), an attacker who flips bits in the ciphertext flips the corresponding plaintext bits predictably, enabling targeted message manipulation without detection. The 'Jwt Attack' tag suggests this fallback is relevant where the library protects JWT-style tokens whose integrity must not be forgeable.

RemediationAI

Vendor-released patch: 1.4.0 - upgrade openssl_encrypt to version 1.4.0 or later, which removes the insecure AES-CTR fallback so that AES-GCM authentication failures abort decryption instead of silently downgrading. Consult the vendor advisory at https://github.com/jahlives/openssl_encrypt/security/advisories/GHSA-w4j7-wfgw-r52w and the VulnCheck writeup at https://www.vulncheck.com/advisories/openssl-encrypt-before-authentication-bypass-via-aes-ctr-fallback. If immediate upgrade is not possible, treat any data decrypted by vulnerable versions as potentially tampered, and protect ciphertext in transit with an authenticated transport such as TLS to deny attackers a modification position (trade-off: does not fix the underlying fallback, only removes the network tampering path); where feasible, wrap or verify messages with an independent HMAC/signature before feeding them to the library so a forged message is rejected upstream (trade-off: requires application changes and correct key management).