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Openssh CVE-2015-5600

HIGH
Permissions, Privileges, and Access Controls (CWE-264)
2015-08-03 cve@mitre.org
8.1
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V8 - Authorization Permission and access control
MITRE ATT&CK

1 technique across 1 tactic: Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 8.1 (HIGH). Attack characteristics: network attack vector, high complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available. EPSS exploitation probability: 73.59%.

Exploit ScenarioDerived

This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the high-severity affected system.

Act Now Prioritize within 24-48h. Why: HIGH severity + EPSS > 10%.
No patch listed yet 73.6% exploitation probability (EPSS)

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AnalysisAI

The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not properly restrict the processing of keyboard-interactive devices within a single connection, which makes it. Rated high severity (CVSS 8.1), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and EPSS exploitation probability 73.6%.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-264. The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not properly restrict the processing of keyboard-interactive devices within a single connection, which makes it easier for remote attackers to conduct brute-force attacks or cause a denial of service (CPU consumption) via a long and duplicative list in the ssh -oKbdInteractiveDevices option, as demonstrated by a modified client that provides a different password for each pam element on this list. Affected products include: Openbsd Openssh. Version information: through 6.9.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.1 HIGH
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
CVSS changed
May 27, 2026 - 19:37 NVD
8.5 (HIGH) 8.1 (HIGH)
CVE Published
Aug 03, 2015 - 01:59 cve.org
HIGH 8.1

DescriptionCVE.org

The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not properly restrict the processing of keyboard-interactive devices within a single connection, which makes it easier for remote attackers to conduct brute-force attacks or cause a denial of service (CPU consumption) via a long and duplicative list in the ssh -oKbdInteractiveDevices option, as demonstrated by a modified client that provides a different password for each pam element on this list.

Threat Intelligence Overview

Threat Score
5.3/10
Composite threat intelligence
EPSS Score
73.6%
Top 1% exploitable
Exploit
POC
Public exploit code exists
Data Quality
4 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC Yes
EPSS 73.6%
Patch available No
Active threat Yes
Deciding rule
HIGH severity + EPSS > 10%
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

134
Low Medium High Critical
KEV: 0
EPSS: +74
CVSS: +40
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Privilege escalation occurs when an attacker leverages flaws in access control mechanisms to gain permissions beyond what they were originally granted.

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)CVE.org

cpe:2.3:a:openbsd:openssh:*:*:*:*:*:*:*:*
CVE-2023-38408 CRITICAL POC
9.8 Jul 20

The PKCS#11 feature in ssh-agent in OpenSSH before 9.3p2 has an insufficiently trustworthy search path, leading to remot

CVE-2023-25136 MEDIUM POC
6.5 Feb 03

OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling. Rated medium se

CVE-2016-6210 MEDIUM POC
5.9 Feb 13

sshd in OpenSSH before 7.3, when SHA256 or SHA512 are used for user password hashing, uses BLOWFISH hashing on a static

CVE-2016-6515 HIGH POC
7.5 Aug 07

The auth_password function in auth-passwd.c in sshd in OpenSSH before 7.3 does not limit password lengths for password a

CVE-2024-6387 HIGH POC
8.1 Jul 01

Remote code execution in OpenSSH's sshd server (regression of CVE-2006-5051) allows unauthenticated remote attackers to

CVE-2019-6111 MEDIUM POC
5.9 Jan 31

An issue was discovered in OpenSSH 7.9. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no

CVE-2025-26465 MEDIUM
6.8 Feb 18

A vulnerability was found in OpenSSH when the VerifyHostKeyDNS option is enabled. Rated medium severity (CVSS 6.8), this

CVE-2023-48795 MEDIUM POC
5.9 Dec 18

The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other products, allows remot

CVE-2016-0777 MEDIUM
6.5 Jan 14

The resend_bytes function in roaming_common.c in the client in OpenSSH 5.x, 6.x, and 7.x before 7.1p2 allows remote serv

CVE-2016-3115 MEDIUM POC
6.4 Mar 22

Multiple CRLF injection vulnerabilities in session.c in sshd in OpenSSH before 7.2p2 allow remote authenticated users to

CVE-2019-6110 MEDIUM POC
6.8 Jan 31

In OpenSSH 7.9, due to accepting and displaying arbitrary stderr output from the server, a malicious server (or Man-in-T

CVE-2025-26466 MEDIUM
5.9 Feb 28

A flaw was found in the OpenSSH package. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, n

References

Advisories & patches
ADVISORY https://vuldb.com/vuln/121583 ADVISORY https://vuldb.com/vuln/76870 ADVISORY https://vuldb.com/vuln/90084 REF http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/auth2-chall.c REF http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/auth2-chall.c.diff?r1=1.42&r2=1.43&f=h REF http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10697 REF http://lists.apple.com/archives/security-announce/2015/Aug/msg00001.html REF http://lists.fedoraproject.org/pipermail/package-announce/2015-August/165170.html REF http://lists.fedoraproject.org/pipermail/package-announce/2015-July/162955.html REF http://lists.opensuse.org/opensuse-security-announce/2015-09/msg00017.html REF http://openwall.com/lists/oss-security/2015/07/23/4 REF http://rhn.redhat.com/errata/RHSA-2016-0466.html REF http://www.oracle.com/technetwork/security-advisory/cpujul2016-2881720.html REF http://www.oracle.com/technetwork/security-advisory/cpujul2018-4258247.html REF http://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html REF http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html REF http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html REF http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html REF http://www.securityfocus.com/bid/75990 REF http://www.securityfocus.com/bid/91787 REF http://www.securityfocus.com/bid/92012 REF http://www.securitytracker.com/id/1032988 REF http://www.ubuntu.com/usn/USN-2710-1 REF http://www.ubuntu.com/usn/USN-2710-2 REF https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf REF https://h20564.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c04952480 REF https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05128992 REF https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05157667 REF https://kc.mcafee.com/corporate/index?page=content&id=SB10136 REF https://kc.mcafee.com/corporate/index?page=content&id=SB10157 REF https://lists.debian.org/debian-lts-announce/2018/09/msg00010.html REF https://security.gentoo.org/glsa/201512-04 REF https://security.netapp.com/advisory/ntap-20151106-0001/ REF https://support.apple.com/kb/HT205031 REF https://www.arista.com/en/support/advisories-notices/security-advisories/1174-security-advisory-12

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