CVE-2016-6515

HIGH

OpenSSH < 7.3 - Denial of Service via Long Password String

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 4 public exploits for CVE-2016-6515. PoCs published by SecPod Research, opsxcq, jptr218.

AI-analyzed exploit summary This exploit targets a CPU consumption vulnerability in OpenSSH before 7.3 by sending a crafted password of 90,000 characters during authentication, causing excessive CPU usage and a denial-of-service condition.

Description

The auth_password function in auth-passwd.c in sshd in OpenSSH before 7.3 does not limit password lengths for password authentication, which allows remote attackers to cause a denial of service (crypt CPU consumption) via a long string.

Exploits (4)

exploitdb WORKING POC
by SecPod Research · pythondoslinux
https://www.exploit-db.com/exploits/40888

This exploit targets a CPU consumption vulnerability in OpenSSH before 7.3 by sending a crafted password of 90,000 characters during authentication, causing excessive CPU usage and a denial-of-service condition.

Classification
Working Poc 95%
Attack Type
Dos
Complexity
Trivial
Reliability
Reliable
Target: OpenSSH before 7.3
No auth needed
Prerequisites: Network access to the target SSH server · Paramiko Python library installed
devstral-2 · analyzed Feb 16, 2026 Full analysis →
nomisec WORKING POC 53 stars
by opsxcq · poc
https://github.com/opsxcq/exploit-CVE-2016-6515

This repository contains a functional exploit for CVE-2016-6515, a denial-of-service vulnerability in OpenSSH versions before 7.3. The exploit leverages the lack of password length limits during authentication, causing excessive CPU consumption via a long password string.

Classification
Working Poc 95%
Attack Type
Dos
Complexity
Trivial
Reliability
Reliable
Target: OpenSSH < 7.3
No auth needed
Prerequisites: Node.js installed · SSH2 library for Node.js
devstral-2 · analyzed Feb 18, 2026 Full analysis →
nomisec WORKING POC 1 stars
by jptr218 · poc
https://github.com/jptr218/openssh_dos

This repository contains a functional proof-of-concept exploit for CVE-2016-6515, which causes a denial-of-service (DoS) in OpenSSH servers by sending an excessively long password during authentication, leading to excessive CPU usage and potential crashes.

Classification
Working Poc 95%
Attack Type
Dos
Complexity
Trivial
Reliability
Reliable
Target: OpenSSH (versions affected by CVE-2016-6515)
No auth needed
Prerequisites: Network access to the target OpenSSH server
devstral-2 · analyzed Feb 18, 2026 Full analysis →
nomisec WORKING POC
by cved-sources · poc
https://github.com/cved-sources/cve-2016-6515

This repository provides a Docker container with a vulnerable version of OpenSSH (7.2p2) to demonstrate CVE-2016-6515, a vulnerability in OpenSSH's PAM authentication. The container runs a vulnerable SSH server, allowing for testing of the exploit.

Classification
Working Poc 90%
Attack Type
Auth Bypass
Complexity
Moderate
Reliability
Reliable
Target: OpenSSH 7.2p2
No auth needed
Prerequisites: Docker environment · Network access to the container
devstral-2 · analyzed Feb 18, 2026 Full analysis →

Scores

CVSS v3 7.5
EPSS 0.5767
EPSS Percentile 99.0%
Attack Vector NETWORK
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Details

CWE
CWE-20
Status published
Products (2)
fedoraproject/fedora 24
openbsd/openssh < 7.2
Published Aug 07, 2016
Tracked Since Feb 18, 2026