CVE-2026-66033: libssh2 Integer Underflow DoS via AES-GCM Cipher Negotiation

Overview

Severity

High (CVSS 7.5)

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploit Status

Not Exploited

Patch Tuesday

2026-Jul

Released

2026-07-26

EPSS Score

0.39% (percentile: 31.3%)

Affected Products (2)

Other

• 21431-17084
• 21559-17084

Revision History

• 2026-07-26: Information published.