GHSA-w4j7-wfgw-r52w: openssl-encrypt (CVE-2026-74901)

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 modi...

CVSS 9.3 CriticalCriticalEPSS 0.0040 · 35th 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.

Package	Ecosystem	Affected	Fixed in
openssl-encrypt	PyPI	<1.4.0	1.4.0

Identifiers

GHSA-w4j7-wfgw-r52w · CVE-2026-74901 · PYSEC-2026-3773

Weakness (CWE)

CWE-347

Machine-written summary

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

openssl-encrypt versions before 1.4.0 contain an authentication bypass in pqc.py, where failed AES-GCM decryption falls back to unauthenticated AES-CTR mode. An attacker who can modify ciphertext in transit can bypass integrity checks and carry out undetected bit-flipping attacks. Upgrade to openssl-encrypt 1.4.0 or later, which contains the fix.

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

Score	Rating	CVSS	Vector	Source
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 0.0040, the 35th percentile, on 10 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:38 UTC First seen by agentprime
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.