SSH improper host validation
Summary
| CVE | CVE-2026-9547 |
|---|---|
| State | PUBLISHED |
| Assigner | curl |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-03 07:16:25 UTC |
| Updated | 2026-09-15 07:16:35 UTC |
| Description | When a libcurl-based application performs transfers via `SCP://` or `SFTP://` and utilizes the `CURLOPT_SSH_KEYFUNCTION` callback, it may silently accept an untrusted server. This vulnerability occurs when a server presents a host key type that does not match the specific key type already recorded for that host in the `known_hosts` file. Instead of rejecting the mismatch, the callback mechanism fails to properly enforce the restriction, allowing the connection to succeed without warning and risking a potential man-in-the-middle attack. |
Risk And Classification
Primary CVSS: v3.1 7.4 HIGH from ADP
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS: 0.003250000 probability, percentile 0.255020000 (date 2026-09-15)
Problem Types: CWE-297 | NVD-CWE-Other | CWE-297 Improper Validation of Certificate with Host Mismatch
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | DECLARED | 7.4 | HIGH | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 7.4 | HIGH | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
HighPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
NoneCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD Known Affected Configurations (CPE 2.3)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Curl | Curl | affected 7.69.0 8.14.2 semver | Not specified |
| CNA | Curl | Curl | affected 8.15.0 8.16.1 semver | Not specified |
| CNA | Curl | Curl | affected 8.17.0 8.20.1 semver | Not specified |
| CNA | Curl | Curl | affected 507cf6a13db0375eadd4655b4c64710db29e9cf2 0b8dbbc63c98777e4584cb9fbd71df3464008ad1 git | Not specified |
| CNA | Curl | Curl | affected 8.20.0 | Not specified |
| CNA | Curl | Curl | affected 8.19.0 | Not specified |
| CNA | Curl | Curl | affected 8.18.0 | Not specified |
| CNA | Curl | Curl | affected 8.17.0 | Not specified |
| CNA | Curl | Curl | affected 8.16.0 | Not specified |
| CNA | Curl | Curl | affected 8.15.0 | Not specified |
| CNA | Curl | Curl | affected 8.14.1 | Not specified |
| CNA | Curl | Curl | affected 8.14.0 | Not specified |
| CNA | Curl | Curl | affected 8.13.0 | Not specified |
| CNA | Curl | Curl | affected 8.12.1 | Not specified |
| CNA | Curl | Curl | affected 8.12.0 | Not specified |
| CNA | Curl | Curl | affected 8.11.1 | Not specified |
| CNA | Curl | Curl | affected 8.11.0 | Not specified |
| CNA | Curl | Curl | affected 8.10.1 | Not specified |
| CNA | Curl | Curl | affected 8.10.0 | Not specified |
| CNA | Curl | Curl | affected 8.9.1 | Not specified |
| CNA | Curl | Curl | affected 8.9.0 | Not specified |
| CNA | Curl | Curl | affected 8.8.0 | Not specified |
| CNA | Curl | Curl | affected 8.7.1 | Not specified |
| CNA | Curl | Curl | affected 8.7.0 | Not specified |
| CNA | Curl | Curl | affected 8.6.0 | Not specified |
| CNA | Curl | Curl | affected 8.5.0 | Not specified |
| CNA | Curl | Curl | affected 8.4.0 | Not specified |
| CNA | Curl | Curl | affected 8.3.0 | Not specified |
| CNA | Curl | Curl | affected 8.2.1 | Not specified |
| CNA | Curl | Curl | affected 8.2.0 | Not specified |
| CNA | Curl | Curl | affected 8.1.2 | Not specified |
| CNA | Curl | Curl | affected 8.1.1 | Not specified |
| CNA | Curl | Curl | affected 8.1.0 | Not specified |
| CNA | Curl | Curl | affected 8.0.1 | Not specified |
| CNA | Curl | Curl | affected 8.0.0 | Not specified |
| CNA | Curl | Curl | affected 7.88.1 | Not specified |
| CNA | Curl | Curl | affected 7.88.0 | Not specified |
| CNA | Curl | Curl | affected 7.87.0 | Not specified |
| CNA | Curl | Curl | affected 7.86.0 | Not specified |
| CNA | Curl | Curl | affected 7.85.0 | Not specified |
| CNA | Curl | Curl | affected 7.84.0 | Not specified |
| CNA | Curl | Curl | affected 7.83.1 | Not specified |
| CNA | Curl | Curl | affected 7.83.0 | Not specified |
| CNA | Curl | Curl | affected 7.82.0 | Not specified |
| CNA | Curl | Curl | affected 7.81.0 | Not specified |
| CNA | Curl | Curl | affected 7.80.0 | Not specified |
| CNA | Curl | Curl | affected 7.79.1 | Not specified |
| CNA | Curl | Curl | affected 7.79.0 | Not specified |
| CNA | Curl | Curl | affected 7.78.0 | Not specified |
| CNA | Curl | Curl | affected 7.77.0 | Not specified |
| CNA | Curl | Curl | affected 7.76.1 | Not specified |
| CNA | Curl | Curl | affected 7.76.0 | Not specified |
| CNA | Curl | Curl | affected 7.75.0 | Not specified |
| CNA | Curl | Curl | affected 7.74.0 | Not specified |
| CNA | Curl | Curl | affected 7.73.0 | Not specified |
| CNA | Curl | Curl | affected 7.72.0 | Not specified |
| CNA | Curl | Curl | affected 7.71.1 | Not specified |
| CNA | Curl | Curl | affected 7.71.0 | Not specified |
| CNA | Curl | Curl | affected 7.70.0 | Not specified |
| CNA | Curl | Curl | affected 7.69.1 | Not specified |
| CNA | Curl | Curl | affected 7.69.0 | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| curl.se/docs/CVE-2026-9547.json | 2499f714-1537-4658-8207-48ae4bb9eae9 | curl.se | Vendor Advisory |
| hackerone.com/reports/3751712 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | hackerone.com | Exploit, Issue Tracking, Third Party Advisory |
| curl.se/docs/CVE-2026-9547.html | 2499f714-1537-4658-8207-48ae4bb9eae9 | curl.se | Patch, Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Joshua Rogers (Aisle Research) (en)
CNA: Joshua Rogers (Aisle Research) (en)
There are currently no legacy QID mappings associated with this CVE.