The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not…
Priority MEDIUM 49CWE-400Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Denial of service, Security bypass
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 16 fixed, 2 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-400 and CWE-264.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.09377 95th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial Red Hat: 2 advisoriesRed Hat: 16 fixed, 2 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
Remediation
Red Hat 2 advisories
- RHSA-2016:0466 Released 2016-03-21 · Red Hat rating Moderateopenssh security update
- Red Hat Enterprise Linux Desktop (v. 6) openssh-5.3p1-114.el6_7, openssh-askpass-5.3p1-114.el6_7, openssh-clients-5.3p1-114.el6_7 +1
- Red Hat Enterprise Linux Desktop Optional (v. 6) openssh-ldap-5.3p1-114.el6_7, pam_ssh_agent_auth-0.9.3-114.el6_7
- Red Hat Enterprise Linux HPC Node (v. 6) openssh-5.3p1-114.el6_7, openssh-clients-5.3p1-114.el6_7, openssh-server-5.3p1-114.el6_7
- Red Hat Enterprise Linux HPC Node Optional (v. 6) openssh-askpass-5.3p1-114.el6_7, openssh-ldap-5.3p1-114.el6_7, pam_ssh_agent_auth-0.9.3-114.el6_7
- Red Hat Enterprise Linux Server (v. 6) openssh-5.3p1-114.el6_7, openssh-askpass-5.3p1-114.el6_7, openssh-clients-5.3p1-114.el6_7 +1
- Red Hat Enterprise Linux Server Optional (v. 6) openssh-ldap-5.3p1-114.el6_7, pam_ssh_agent_auth-0.9.3-114.el6_7, pam_ssh_agent_auth-0.9.3-114.el6_7.ppc
- Red Hat Enterprise Linux Workstation (v. 6) openssh-5.3p1-114.el6_7, openssh-askpass-5.3p1-114.el6_7, openssh-clients-5.3p1-114.el6_7 +1
- Red Hat Enterprise Linux Workstation Optional (v. 6) openssh-ldap-5.3p1-114.el6_7, pam_ssh_agent_auth-0.9.3-114.el6_7
- RHSA-2015:2088 Released 2015-11-19 · Red Hat rating Moderateopenssh security, bug fix, and enhancement update
- Red Hat Enterprise Linux Client (v. 7) openssh-6.6.1p1-22.el7, openssh-askpass-6.6.1p1-22.el7, openssh-clients-6.6.1p1-22.el7 +2
- Red Hat Enterprise Linux Client Optional (v. 7) openssh-ldap-6.6.1p1-22.el7, openssh-server-sysvinit-6.6.1p1-22.el7, pam_ssh_agent_auth-0.9.3-9.22.el7
- Red Hat Enterprise Linux ComputeNode (v. 7) openssh-6.6.1p1-22.el7, openssh-clients-6.6.1p1-22.el7, openssh-keycat-6.6.1p1-22.el7 +1
- Red Hat Enterprise Linux ComputeNode Optional (v. 7) openssh-askpass-6.6.1p1-22.el7, openssh-ldap-6.6.1p1-22.el7, openssh-server-sysvinit-6.6.1p1-22.el7 +1
- Red Hat Enterprise Linux Server (v. 7) openssh-6.6.1p1-22.el7, openssh-askpass-6.6.1p1-22.el7, openssh-clients-6.6.1p1-22.el7 +2
- Red Hat Enterprise Linux Server Optional (v. 7) openssh-askpass-6.6.1p1-22.el7, openssh-ldap-6.6.1p1-22.el7, openssh-server-sysvinit-6.6.1p1-22.el7 +2
- Red Hat Enterprise Linux Workstation (v. 7) openssh-6.6.1p1-22.el7, openssh-askpass-6.6.1p1-22.el7, openssh-clients-6.6.1p1-22.el7 +2
- Red Hat Enterprise Linux Workstation Optional (v. 7) openssh-ldap-6.6.1p1-22.el7, openssh-server-sysvinit-6.6.1p1-22.el7, pam_ssh_agent_auth-0.9.3-9.22.el7
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 4 | Affected | No fix planned: Will not fix |
| Red Hat Enterprise Linux 5 | Affected | No fix planned: Will not fix |
| Red Hat Enterprise Linux Client (v. 7) | Fixed | RHSA-2015:2088 |
| Red Hat Enterprise Linux Client Optional (v. 7) | Fixed | RHSA-2015:2088 |
| Red Hat Enterprise Linux ComputeNode (v. 7) | Fixed | RHSA-2015:2088 |
| Red Hat Enterprise Linux ComputeNode Optional (v. 7) | Fixed | RHSA-2015:2088 |
| Red Hat Enterprise Linux Desktop (v. 6) | Fixed | RHSA-2016:0466 |
| Red Hat Enterprise Linux Desktop Optional (v. 6) | Fixed | RHSA-2016:0466 |
| Red Hat Enterprise Linux HPC Node (v. 6) | Fixed | RHSA-2016:0466 |
| Red Hat Enterprise Linux HPC Node Optional (v. 6) | Fixed | RHSA-2016:0466 |
| Red Hat Enterprise Linux Server (v. 6) | Fixed | RHSA-2016:0466 |
| Red Hat Enterprise Linux Server (v. 7) | Fixed | RHSA-2015:2088 |
| Red Hat Enterprise Linux Server Optional (v. 6) | Fixed | RHSA-2016:0466 |
| Red Hat Enterprise Linux Server Optional (v. 7) | Fixed | RHSA-2015:2088 |
| Red Hat Enterprise Linux Workstation (v. 6) | Fixed | RHSA-2016:0466 |
| Red Hat Enterprise Linux Workstation (v. 7) | Fixed | RHSA-2015:2088 |
| Red Hat Enterprise Linux Workstation Optional (v. 6) | Fixed | RHSA-2016:0466 |
| Red Hat Enterprise Linux Workstation Optional (v. 7) | Fixed | RHSA-2015:2088 |
Timeline
- 2026-10-02 Threatist record created from CVE-2015-5600
- 2026-10-03 Alias added: GHSA-6x25-gfx2-5crp
References
Exploit 1
Advisory 8
Other 20
- http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.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://kc.mcafee.com/corporate/index?page=content&id=SB10136
- https://security.netapp.com/advisory/ntap-20151106-0001/
- 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://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/auth2-chall.c
- https://kc.mcafee.com/corporate/index?page=content&id=SB10157
- https://h20564.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c04952480
- https://support.apple.com/kb/HT205031
- [debian-lts-announce] 20180910 [SECURITY] [DLA 1500-1] openssh security update
- [oss-security] 20150723 Re: CVE Request for OpenSSH vulnerability - authentication limits bypass
- http://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html
- https://www.arista.com/en/support/advisories-notices/security-advisories/1174-security-advisory-12
- https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
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- TI-2023-10601 OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during… CVSS 3.1MEDIUM 6.5
- TI-2018-11033 OpenSSH through 7.7 is prone to a user enumeration vulnerability due to not delaying… CVSS 3.1MEDIUM 5.9
- TI-2016-08105 Untrusted search path vulnerability in ssh-agent.c in ssh-agent in OpenSSH before 7.4… CVSS 3.1HIGH 7.3
- TI-2023-28040 In ssh in OpenSSH before 9.6, OS command injection might occur if a user name or host… CVSS 3.1MEDIUM 6.5
Sources
- CVE-2015-5600 · CVE Program
- CVE-2015-5600 · NVD
- FIRST EPSS
- GHSA-6x25-gfx2-5crp · GitHub Advisory Database · CC BY 4.0
- CVE-2015-5600 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences