Vulnerability · Published Aug 17, 2026 · Assigned by VulnCheck

CVE-2026-74889openssl_encrypt before 1.4.0 Weak Key Derivation via HKDF

Critical 9.8

In plain English

A critical-severity security flaw in openssl_encrypt from jahlives. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.8Critical

Exploit odds (30 days)0.3%top 71.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

openssl_encrypt versions before 1.4.0 use HKDF with no salt and static info parameter in key normalization functions, reducing entropy extraction and determinism. Attackers can exploit predictable key derivation with identical inputs to weaken cryptographic security against multi-target attacks.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
PyPI	openssl-encrypt	1.4.0	PYSEC-2026-3765

Affected products (as reported)

Vendor	Product	Versions
jahlives	openssl_encrypt	0 – before 1.4.0

Weakness: CWE-326 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

GitHub Security Advisory (GHSA-j9mh-57cc-665x) vendor-advisory
VulnCheck Advisory: openssl_encrypt before 1.4.0 Weak Key Derivation via HKDF third-party-advisory