CVE-2015-6563: The monitor component in sshd in OpenSSH before 7.0 on non-OpenBSD platforms accepts extraneous username data in MONITOR_REQ_PAM_INIT_CTX…
Noroxi assessment
Priority: Monitor (action score 25/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.38% (FIRST EPSS).
- Someone with local access to the system can trigger it. Administrator privileges are required. No user action is required. Special conditions such as timing or configuration are required.
- Fixed version: openssh (Debian:12) 1:6.9p1-1; openssh (Debian:8) 1:6.7p1-5+deb8u6; openssh (Red Hat:enterprise_linux:6::client) 0:5.3p1-117.el6.
Low priority for now. Upgrade to openssh (Debian:12) 1:6.9p1-1; openssh (Debian:8) 1:6.7p1-5+deb8u6; openssh (Red Hat:enterprise_linux:6::client) 0:5.3p1-117.el6 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
The monitor component in sshd in OpenSSH before 7.0 on non-OpenBSD platforms accepts extraneous username data in MONITOR_REQ_PAM_INIT_CTX requests, which allows local users to conduct impersonation attacks by leveraging any SSH login access in conjunction with control of the sshd uid to send a crafted MONITOR_REQ_PWNAM request, related to monitor.c and monitor_wrap.c.
- Published
- Aug 23, 2015
- Updated
- Jun 16, 2026
- EPSS
- 0.3% · 32th percentile
- CWE
- CWE-20
Report tools
Action score
25
Low priority for now.
- CVSS
- 25 / 40 · 6.4 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.3%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Is OpenSSH on your server exposed to the internet?Run a port scan
Is your version affected? Check itNoroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
Is OpenSSH on your server exposed to the internet?
The free port scanner finds the open ports on your server and matches the service versions it can read against known vulnerabilities. No account needed.
Run a port scanAffected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- apple mac os xup to 10.11.0 inclusive
- openbsd opensshup to 6.9 inclusive
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | openssh | before 1:6.9p1-1 | 1:6.9p1-1 |
| Debian:8 | openssh | before 1:6.7p1-5+deb8u6 | 1:6.7p1-5+deb8u6 |
| Red Hat:enterprise_linux:6::client | openssh | before 0:5.3p1-117.el6 | 0:5.3p1-117.el6 |
| Red Hat:enterprise_linux:6::client | openssh-askpass | before 0:5.3p1-117.el6 | 0:5.3p1-117.el6 |
| Red Hat:enterprise_linux:6::client | openssh-clients | before 0:5.3p1-117.el6 | 0:5.3p1-117.el6 |
| Red Hat:enterprise_linux:6::client | openssh-debuginfo | before 0:5.3p1-117.el6 | 0:5.3p1-117.el6 |
| Red Hat:enterprise_linux:6::client | openssh-ldap | before 0:5.3p1-117.el6 | 0:5.3p1-117.el6 |
| Red Hat:enterprise_linux:6::client | openssh-server | before 0:5.3p1-117.el6 | 0:5.3p1-117.el6 |
| Red Hat:enterprise_linux:6::client | pam_ssh_agent_auth | before 0:0.9.3-117.el6 | 0:0.9.3-117.el6 |
| Red Hat:enterprise_linux:7::client | openssh | before 0:6.6.1p1-22.el7 | 0:6.6.1p1-22.el7 |
| Red Hat:enterprise_linux:7::client | openssh-askpass | before 0:6.6.1p1-22.el7 | 0:6.6.1p1-22.el7 |
| Red Hat:enterprise_linux:7::client | openssh-clients | before 0:6.6.1p1-22.el7 | 0:6.6.1p1-22.el7 |
| Red Hat:enterprise_linux:7::client | openssh-debuginfo | before 0:6.6.1p1-22.el7 | 0:6.6.1p1-22.el7 |
| Red Hat:enterprise_linux:7::client | openssh-keycat | before 0:6.6.1p1-22.el7 | 0:6.6.1p1-22.el7 |
| Red Hat:enterprise_linux:7::client | openssh-ldap | before 0:6.6.1p1-22.el7 | 0:6.6.1p1-22.el7 |
| Red Hat:enterprise_linux:7::client | openssh-server | before 0:6.6.1p1-22.el7 | 0:6.6.1p1-22.el7 |
| Red Hat:enterprise_linux:7::client | openssh-server-sysvinit | before 0:6.6.1p1-22.el7 | 0:6.6.1p1-22.el7 |
| Red Hat:enterprise_linux:7::client | pam_ssh_agent_auth | before 0:0.9.3-9.22.el7 | 0:0.9.3-9.22.el7 |
| SUSE:Linux Enterprise Desktop 11 SP3 | openssh | before 6.2p2-0.21.1 | 6.2p2-0.21.1 |
| SUSE:Linux Enterprise Desktop 11 SP3 | openssh-askpass-gnome | before 6.2p2-0.21.3 | 6.2p2-0.21.3 |
| SUSE:Linux Enterprise Desktop 11 SP4 | openssh | before 6.6p1-13.1 | 6.6p1-13.1 |
| SUSE:Linux Enterprise Desktop 11 SP4 | openssh-askpass-gnome | before 6.6p1-13.3 | 6.6p1-13.3 |
| SUSE:Linux Enterprise Desktop 12 | openssh | before 6.6p1-29.1 | 6.6p1-29.1 |
| SUSE:Linux Enterprise Desktop 12 | openssh-askpass-gnome | before 6.6p1-29.1 | 6.6p1-29.1 |
Same product
openbsd: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-123158sshd in OpenSSH before 10.6p2 on Linux, when musl libc is used without PAM, lacks a workaround for a password authentication bypass…KEV68This week
- CVE-2023-38408The PKCS#11 feature in ssh-agent in OpenSSH before 9.3p2 has an insufficiently trustworthy search path, leading to remote code execution if…63This week
- CVE-2018-15473OpenSSH through 7.7 is prone to a user enumeration vulnerability due to not delaying bailout for an invalid authenticating user until after…60This week
Published before and after this one in the same product
- ← EarlierCVE-2015-5352Aug 2, 2015 · The x11_open_helper function in channels.c in ssh in OpenSSH before 6.9, when ForwardX11Trusted mode is not used, lacks a check of the…18Monitor
- ← EarlierCVE-2015-5600Aug 2, 2015 · The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not properly restrict the processing of…35Monitor
- Later →CVE-2015-6564Aug 23, 2015 · Use-after-free vulnerability in the mm_answer_pam_free_ctx function in monitor.c in sshd in OpenSSH before 7.0 on non-OpenBSD platforms…28Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:openssh | 1:6.9p1-1 · Debian:12 | Package registry (OSV) |
| red hat:openssh | 0:6.6.1p1-22.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-askpass | 0:6.6.1p1-22.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-clients | 0:6.6.1p1-22.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-debuginfo | 0:6.6.1p1-22.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-keycat | 0:6.6.1p1-22.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-ldap | 0:6.6.1p1-22.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-server | 0:6.6.1p1-22.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-server-sysvinit | 0:6.6.1p1-22.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:pam_ssh_agent_auth | 0:0.9.3-9.22.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| suse:openssh | 6.6p1-29.1 · SUSE:Linux Enterprise Desktop 12 | Package registry (OSV) |
| suse:openssh-askpass-gnome | 6.6p1-29.1 · SUSE:Linux Enterprise Desktop 12 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Not on record for this CVE: EPSS history · researcher credit · variant or chain candidate · public bounty program.
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- Administrator privileges are required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- High
- Privileges required
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-20 · Improper Input ValidationCVSS vector
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Server Side Include (SSI) InjectionCAPEC-101likelihood: High · High
- Cross Zone ScriptingCAPEC-104likelihood: Medium · High
- Command Line Execution through SQL InjectionCAPEC-108likelihood: Low · Very High
- Object Relational Mapping InjectionCAPEC-109likelihood: Low · High
- SQL Injection through SOAP Parameter TamperingCAPEC-110likelihood: High · Very High
- Double EncodingCAPEC-120likelihood: Low · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
ATT&CK techniques
- Obfuscated Files or InformationT1027
- Masquerading: Invalid Code SignatureT1036.001
- Steal Web Session CookieT1539
- Subvert Trust Controls: Code SigningT1553.002
- Impair Defenses:Impair Command History LoggingT1562.003
- Hijack Execution Flow:Dynamic Linker HijackingT1574.006
- Hijack Execution Flow:Path Interception by PATH Environment VariableT1574.007
Change log (1)
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (17 more)Show less
- lists.fedoraproject.org/pipermail/package-announce/2015-August/165170.html
- lists.opensuse.org/opensuse-security-announce/2015-09/msg00017.html
- rhn.redhat.com/errata/RHSA-2016-0741.html
- seclists.org/fulldisclosure/2015/Aug/54
- www.openssh.com/txt/release-7.0
- www.openwall.com/lists/oss-security/2015/08/22/1
- www.oracle.com/technetwork/topics/security/bulletinjan2016-2867206.html
- www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
- www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html
- www.securityfocus.com/bid/76317
- cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
- github.com/openssh/openssh-portable/commit/d4697fe9a28dab7255c60433e4dd23cf7fce8a8b
- lists.debian.org/debian-lts-announce/2018/09/msg00010.html
- security.gentoo.org/glsa/201512-04
- security.netapp.com/advisory/ntap-20180201-0002/
- support.apple.com/HT205375
- www.broadcom.com/support/fibre-channel-networking/security-advisories/brocade-security-advisory-2019-766
Vendor advisories and official records. Exploit/PoC links are deliberately left out.