CVE-2026-55199: libssh2 - Pre-Authentication DoS via SSH_MSG_EXT_INFO Handler

Overview

Severity

Medium (CVSS 5.9)

CVSS Vector

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

Exploit Status

Not Exploited

Patch Tuesday

2026-Jun

Released

2026-06-27

Last Updated

2026-07-06

EPSS Score

0.92% (percentile: 57.1%)

Affected Products (5)

Other

• 21431-17084
• 21485-17084
• 21559-17084
• 21318-17084
• 20881-17084

Revision History

• 2026-06-27: Information published.
• 2026-06-28: Information published.
• 2026-07-03: Information published.
• 2026-07-03: Information published.
• 2026-07-06: Information published.