CVE-2026-74900CWE-391

CVE-2026-74900

Critical · published August 17, 2026

CVSS v3.1
9.8
EPSS
0%
Percentile
26.5
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
9.3 · 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
EPSS
0.00337 · 26.5th percentile
Weakness
CWE-391 · Unchecked Error Condition
Published
2026-08-17T15:16Z
Affected products (1)
ProductVersionsFixed in
jahlives/openssl_encrypt< 1.4.01.4.0
References (2)
https://github.com/jahlives/openssl_encrypt/security/advisories/GHSA-p3gq-pcg9-qvfv · [email protected]https://www.vulncheck.com/advisories/openssl-encrypt-before-weak-shared-secret-via-pqc-simulation-mode · [email protected]
EPSS history
Timeline
  • 17 AUG 11:04Z
    openssl_encrypt before 1.4.0 Weak Shared Secret via PQC Simulation Mode
    cvelistv5