CVE-2023-51384: In ssh-agent in OpenSSH before 9.6, certain destination constraints can be incompletely applied.
Noroxi assessment
Priority: Monitor (action score 22/100)
- 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: 0.42% (FIRST EPSS).
- Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
- Fixed version: openssh (Alpine:v3.16) 9.0_p1-r5; openssh (Alpine:v3.17) 9.1_p1-r5; openssh (Alpine:v3.19) 9.6_p1-r0.
Low priority for now. Upgrade to openssh (Alpine:v3.16) 9.0_p1-r5; openssh (Alpine:v3.17) 9.1_p1-r5; openssh (Alpine:v3.19) 9.6_p1-r0 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
In ssh-agent in OpenSSH before 9.6, certain destination constraints can be incompletely applied. When destination constraints are specified during addition of PKCS#11-hosted private keys, these constraints are only applied to the first key, even if a PKCS#11 token returns multiple keys.
- Published
- Dec 18, 2023
- Updated
- Oct 15, 2026
- EPSS
- 0.4% · 36th percentile
- CWE
- CWE-284
Report tools
Action score
22
Monitor
Low priority for now.
- CVSS
- 22 / 40 · 5.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 5.5
- CNA · mitre
- 5.5
- agree
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
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.
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Noroxi 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.
| Vendor | Product | CPE |
|---|---|---|
| openbsd | openssh | cpe:2.3:a:openbsd:openssh |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
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.
- debian debian linux11.0
- debian debian linux12.0
- openbsd openssh8.9 and later · before 9.6
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.16 | openssh | from 8.9 · before 9.0_p1-r5 | 9.0_p1-r5 |
| Alpine:v3.17 | openssh | from 8.9 · before 9.1_p1-r5 | 9.1_p1-r5 |
| Alpine:v3.19 | openssh | from 8.9 · before 9.6_p1-r0 | 9.6_p1-r0 |
| Debian:12 | openssh | before 1:9.2p1-2+deb12u2 | 1:9.2p1-2+deb12u2 |
| Debian:13 | openssh | before 1:9.6p1-1 | 1:9.6p1-1 |
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-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
- 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 us60This week
Published before and after this one in the same product
- ← EarlierCVE-2023-25136Feb 3, 2023 · OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling.53Plan
- ← EarlierCVE-2023-28531Mar 17, 2023 · ssh-add in OpenSSH before 9.3 adds smartcard keys to ssh-agent without the intended per-hop destination constraints.40Plan
- Later →CVE-2023-51385Dec 18, 2023 · In ssh in OpenSSH before 9.6, OS command injection might occur if a user name or host name has shell metacharacters, and this name is refere32Monitor
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 |
|---|---|---|
| alpine:openssh | 9.0_p1-r5 · Alpine:v3.16 | Package registry (OSV) |
| debian:openssh | 1:9.2p1-2+deb12u2 · Debian: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.
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.
- CVE-2023-28531276 days apartssh-add in OpenSSH before 9.3 adds smartcard keys to ssh-agent without the intended per-hop destination constraints.40Plan
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
- Someone with local access to the system can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-284 · Improper Access ControlCVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
nvd-primary
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)
- Embedding Scripts within ScriptsCAPEC-19likelihood: High · High
- Malicious Logic InsertionCAPEC-441likelihood: Medium · High
- Modification of Windows Service ConfigurationCAPEC-478likelihood: Low · High
- Malicious Root CertificateCAPEC-479likelihood: Low · Low
- Intent SpoofCAPEC-502
- WebView ExposureCAPEC-503
- Data Injected During ConfigurationCAPEC-536likelihood: Low · High
- Incomplete Data Deletion in a Multi-Tenant EnvironmentCAPEC-546likelihood: Low · Medium
ATT&CK techniques
- RootkitT1014
- Obfuscated Files or Information: Embedded PayloadsT1027.009
- Boot or Logon Initialization ScriptsT1037
- Taint shared contentT1080
- Server Software Component: Terminal Services DLLT1505.005
- Pre-OS Boot:BootkitT1542.003
- Create or Modify System ProcessT1543
- Create or Modify System Process: Launch AgentT1543.001
- Create or Modify System Process:Windows ServiceT1543.003
- Create or Modify System Process: Launch DaemonT1543.004
- Event Triggered Execution:Change Default File AssociationT1546.001
- Event Triggered Execution:.bash_profile and .bashrcT1546.004
- Event Triggered Execution: Accessibility FeaturesT1546.008
- Event Triggered Execution: Installer PackagesT1546.016
- Boot or Logon Autostart ExecutionT1547
- Boot or Logon Autostart Execution:Kernel Modules and ExtensionsT1547.006
Change log
- Fix✗ → ✓
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References
Show all references (11 more)Show less
- github.com/openssh/openssh-portable/commit/881d9c6af9da4257c69c327c4e2f1508b2fa754b
- security.netapp.com/advisory/ntap-20240105-0005/
- support.apple.com/kb/HT214084
- www.debian.org/security/2023/dsa-5586
- www.openssh.com/txt/release-9.6
- www.openwall.com/lists/oss-security/2023/12/18/2
- cert-portal.siemens.com/productcert/html/ssa-019113.html
- cert-portal.siemens.com/productcert/html/ssa-082556.html
- cert-portal.siemens.com/productcert/html/ssa-457936.html
- cert-portal.siemens.com/productcert/html/ssa-769027.html
- cert-portal.siemens.com/productcert/html/ssa-794697.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.