What’s Vulnerable › Vulnerabilities

CVE-2026-74900: openssl_encrypt before 1.4.0 Weak Shared Secret via PQC Simulation Mode

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% 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-391

Description

openssl_encrypt versions before 1.4.0 contain a critical vulnerability in pqc.py where KEM decapsulation failures silently fall back to simulation mode, generating a deterministic shared secret from only 16 bytes of the private key and publicly available encapsulated key data. Attackers who obtain 16 bytes of the private key can compute the shared secret and decrypt all ciphertext, as the fallback triggers on any KEM failure without raising an error.

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-p3gq-pcg9-qvfv
• https://www.vulncheck.com/advisories/openssl-encrypt-before-weak-shared-secret-via-pqc-simulation-mode

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