The client in OpenSSH before 7.2 mishandles failed cookie generation for untrusted X11 forwarding and relies on the local X11 server for acc
The client in OpenSSH before 7.2 mishandles failed cookie generation for untrusted X11 forwarding and relies on the local X11 server for access-control decisions, which allows remote X11 clients to trigger a fallback and obtain trusted X11 forwarding privileges by leveraging configuration issues on this X11 server, as demonstrated by lack of the SECURITY extension on this X11 server.
- Published
- Apr 11, 2017
- Updated
- Jun 16, 2026
- EPSS
- 13.7% · 96th percentile
- CWE
- CWE-287
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Report tools
Action score
43
Plan
Add it to your regular patch cycle.
- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 4 / 30 · 13.7%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| openbsd | openssh | cpe:2.3:a:openbsd:openssh |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| oracle | linux | cpe:2.3:o:oracle:linux |
| redhat | enterprise linux desktop | cpe:2.3:o:redhat:enterprise_linux_desktop |
| redhat | enterprise linux eus | cpe:2.3:o:redhat:enterprise_linux_eus |
| redhat | enterprise linux server | cpe:2.3:o:redhat:enterprise_linux_server |
| redhat | enterprise linux server aus | cpe:2.3:o:redhat:enterprise_linux_server_aus |
| redhat | enterprise linux server tus | cpe:2.3:o:redhat:enterprise_linux_server_tus |
| redhat | enterprise linux workstation | cpe:2.3:o:redhat:enterprise_linux_workstation |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux8.0
- openbsd opensshbefore 7.2
- oracle linux6
- oracle linux7
- redhat enterprise linux desktop6.0
- redhat enterprise linux desktop7.0
- redhat enterprise linux eus7.2
- redhat enterprise linux eus7.3
- redhat enterprise linux eus7.4
- redhat enterprise linux eus7.5
- redhat enterprise linux eus7.6
- redhat enterprise linux eus7.7
- redhat enterprise linux server6.0
- redhat enterprise linux server7.0
- redhat enterprise linux server aus7.2
- redhat enterprise linux server aus7.3
- redhat enterprise linux server aus7.4
- redhat enterprise linux server aus7.6
- redhat enterprise linux server aus7.7
- redhat enterprise linux server tus7.2
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 1:7.2p1-1 | 1:7.2p1-1 |
| 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 0:6.6.1p1-25.el7_2 | 0:6.6.1p1-25.el7_2 |
| Red Hat:enterprise_linux:7::client | openssh-askpass | before 0:6.6.1p1-25.el7_2 | 0:6.6.1p1-25.el7_2 |
| Red Hat:enterprise_linux:7::client | openssh-clients | before 0:6.6.1p1-25.el7_2 | 0:6.6.1p1-25.el7_2 |
| Red Hat:enterprise_linux:7::client | openssh-debuginfo | before 0:6.6.1p1-25.el7_2 | 0:6.6.1p1-25.el7_2 |
| Red Hat:enterprise_linux:7::client | openssh-keycat | before 0:6.6.1p1-25.el7_2 | 0:6.6.1p1-25.el7_2 |
| Red Hat:enterprise_linux:7::client | openssh-ldap | before 0:6.6.1p1-25.el7_2 | 0:6.6.1p1-25.el7_2 |
| Red Hat:enterprise_linux:7::client | openssh-server | before 0:6.6.1p1-25.el7_2 | 0:6.6.1p1-25.el7_2 |
| Red Hat:enterprise_linux:7::client | openssh-server-sysvinit | before 0:6.6.1p1-25.el7_2 | 0:6.6.1p1-25.el7_2 |
| Red Hat:enterprise_linux:7::client | pam_ssh_agent_auth | before 0:0.9.3-9.25.el7_2 | 0:0.9.3-9.25.el7_2 |
| SUSE:Linux Enterprise Desktop 12 | openssh | before 6.6p1-42.1 | 6.6p1-42.1 |
| SUSE:Linux Enterprise Desktop 12 | openssh-askpass-gnome | before 6.6p1-42.1 | 6.6p1-42.1 |
| SUSE:Linux Enterprise Server 11 SP4 | openssh | before 6.6p1-21.1 | 6.6p1-21.1 |
| SUSE:Linux Enterprise Server 11 SP4 | openssh-askpass-gnome | before 6.6p1-21.3 | 6.6p1-21.3 |
| SUSE:Linux Enterprise Server 11-SECURITY | openssh-openssl1 | before 6.6p1-15.1 | 6.6p1-15.1 |
| SUSE:OpenStack Cloud 5 | openssh | before 6.2p2-0.33.2 | 6.2p2-0.33.2 |
+1
Same product
openbsd: all recordsOther highest-scoring records for the same primary product.
- 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-2023-25136OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling.53Plan
- 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 51Plan
- CVE-2016-6210sshd in OpenSSH before 7.3, when SHA256 or SHA512 are used for user password hashing, uses BLOWFISH hashing on a static password when the us50Plan
- CVE-2016-6515The auth_password function in auth-passwd.c in sshd in OpenSSH before 7.3 does not limit password lengths for password authentication, which48Plan
- CVE-2002-0640Buffer overflow in sshd in OpenSSH 2.3.1 through 3.3 may allow remote attackers to execute arbitrary code via a large number of responses du48Plan
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 | 1:7.2p1-1 · Debian:12 | Package registry (OSV) |
| red hat:openssh | 0:6.6.1p1-25.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-askpass | 0:6.6.1p1-25.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-clients | 0:6.6.1p1-25.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-debuginfo | 0:6.6.1p1-25.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-keycat | 0:6.6.1p1-25.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-ldap | 0:6.6.1p1-25.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-server | 0:6.6.1p1-25.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:openssh-server-sysvinit | 0:6.6.1p1-25.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:pam_ssh_agent_auth | 0:0.9.3-9.25.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| suse:openssh | 6.6p1-42.1 · SUSE:Linux Enterprise Desktop 12 | Package registry (OSV) |
| suse:openssh-askpass-gnome | 6.6p1-42.1 · SUSE:Linux Enterprise Desktop 12 | Package registry (OSV) |
| suse:openssh-openssl1 | 6.6p1-15.1 · SUSE:Linux Enterprise Server 11-SECURITY | 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.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
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
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-287 · Improper AuthenticationCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Root cause
Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.
The bug in code
The whole CWE-287 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
app.use("/admin", requireSession, adminRouter);
// Route added later skips the middlewareapp.post("/admin-api/config", updateConfig);Fixed
const admin = express.Router();admin.use(requireSession, requireRole("admin"));
admin.post("/config", updateConfig);app.use("/admin", admin);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)
- Authentication AbuseCAPEC-114Medium
- Authentication BypassCAPEC-115Medium
- Identity SpoofingCAPEC-151likelihood: Medium · Medium
- Fake the Source of DataCAPEC-194Medium
- Exploiting Trust in ClientCAPEC-22likelihood: High · High
- Utilizing REST's Trust in the System Resource to Obtain Sensitive DataCAPEC-57likelihood: Medium · Very High
- Session HijackingCAPEC-593likelihood: High · Very High
- Token ImpersonationCAPEC-633Medium
ATT&CK techniques
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- openwall.com/lists/oss-security/2016/01/15/13
- rhn.redhat.com/errata/RHSA-2016-0465.html
- rhn.redhat.com/errata/RHSA-2016-0741.html
- www.openssh.com/txt/release-7.2
- www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
- www.securityfocus.com/bid/84427
- www.securitytracker.com/id/1034705
- anongit.mindrot.org/openssh.git/commit/?id=ed4ce82dbfa8a3a3c8ea6fa0db113c71e234416c
- bugzilla.redhat.com/show_bug.cgi?id=1298741
- cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
- lists.debian.org/debian-lts-announce/2018/09/msg00010.html
- security.gentoo.org/glsa/201612-18
Vendor advisories and official records. Exploit/PoC links are deliberately left out.