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Vulnerability record · CVE-2026-74900 · published 17 August 2026

CVE-2026-74900: Jahlives openssl encrypt vulnerability

JJahlives · Openssl Encrypt

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.

9.3 CVSS 4.0 Critical EPSS 0.56% · top 55.7% CWE-391 · CWE-391
9.3CVSS 4.0 base score
0.56%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
1 Sep 2026Last modified by NVD

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.

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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/jahlives/openssl_encrypt/security/advisories/GHSA-p3gq-pcg9-qvfv MitigationVendor Advisory
https://www.vulncheck.com/advisories/openssl-encrypt-before-weak-shared-secret-via-pqc-simulation-mode Third Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-74900), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.