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Advisory record · GHSA-p3gq-pcg9-qvfv

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 fro...

CVSS 9.3 CriticalCriticalEPSS 0.0056 · 46th percentile

Critical, because:

  • CVSS score 9.3: 9.0 or more.

How we decide what’s critical

Published by the GitHub Advisory Database at 17 Aug 2026, 11:16 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
openssl-encryptPyPI<1.4.01.4.0
Identifiers
GHSA-p3gq-pcg9-qvfv · CVE-2026-74900 · PYSEC-2026-3772
Weakness (CWE)
CWE-391
Tags
Published
17 Aug 2026
Updated
2 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

openssl_encrypt versions before 1.4.0 have a flaw in pqc.py where KEM decapsulation failures silently fall back to a simulation mode that derives a deterministic shared secret from 16 bytes of the private key and public encapsulated key data. An attacker who obtains those 16 bytes of the private key can compute the shared secret and decrypt all ciphertext. Upgrade to version 1.4.0 or later.

Written 5 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
9.3 Critical 4.0 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 CNA (VulnCheck)
  • CISA KEV Not listed.
  • EPSS 0.0056, the 46th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:38 UTC First seen by agentprime
  2. 31 Oct 2026, 14:38 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.