Vulnerability · Published Aug 17, 2026 · Assigned by VulnCheck

CVE-2026-74899openssl_encrypt before 1.4.0 Sandbox Escape via Type Hierarchy

Critical 9.8

In plain English

A critical-severity security flaw in openssl_encrypt from jahlives. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.8% (higher than 55% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.8Critical

Exploit odds (30 days)0.8%top 44.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

openssl_encrypt versions before 1.4.0 contain a sandbox escape vulnerability in IsolatedPluginExecutor that exposes Python type objects in restricted exec() builtins. Attackers can traverse the Python class hierarchy via __class__.__mro__.__subclasses__() to access system functions and execute arbitrary OS commands.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
PyPI	openssl-encrypt	1.4.0	PYSEC-2026-3727

Affected products (as reported)

Vendor	Product	Versions
jahlives	openssl_encrypt	0 – before 1.4.0

Weakness: CWE-95 · 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-m25m-ggxg-239c) vendor-advisory
VulnCheck Advisory: openssl_encrypt before 1.4.0 Sandbox Escape via Type Hierarchy third-party-advisory
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-43jx-gxq4-jpjc exploit