DEBIAN-CVE-2026-55199

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Source

https://security-tracker.debian.org/tracker/CVE-2026-55199

Import Source

https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-55199.json

JSON Data

https://api.test.osv.dev/v1/vulns/DEBIAN-CVE-2026-55199

Upstream

CVE-2026-55199

Published

2026-06-17T20:17:28Z

Modified

2026-08-27T23:06:13Z

Severity

7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator

Summary

[none]

Details

libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSH_MSG_EXT_INFO handler in src/packet.c that allows a malicious SSH server to cause a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can set nr_extensions to 0xFFFFFFFF during key exchange, causing the client to spin in a tight CPU loop for over 60 seconds because return values from _libssh2_get_string() are unchecked and the session timeout does not apply to CPU-bound loops.

References

https://security-tracker.debian.org/tracker/CVE-2026-55199

Affected packages

Debian:13 / libssh2

Package

Name: libssh2
Purl: pkg:deb/debian/libssh2?arch=source&distro=trixie

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Fixed

1.11.1-1+deb13u1

Affected versions

1.*

1.11.1-1

Ecosystem specific

{
    "urgency": "not yet assigned"
}

Database specific

source

"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-55199.json"

Debian:14 / libssh2