FKIE_CVE-2026-9547
Vulnerability from fkie_nvd - Published: 2026-07-03 07:16 - Updated: 2026-07-06 18:20
Severity
Summary
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.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "curl",
"vendor": "curl",
"versions": [
{
"lessThanOrEqual": "8.20.0",
"status": "affected",
"version": "8.20.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.19.0",
"status": "affected",
"version": "8.19.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.18.0",
"status": "affected",
"version": "8.18.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.17.0",
"status": "affected",
"version": "8.17.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.16.0",
"status": "affected",
"version": "8.16.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.15.0",
"status": "affected",
"version": "8.15.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.14.1",
"status": "affected",
"version": "8.14.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.14.0",
"status": "affected",
"version": "8.14.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.13.0",
"status": "affected",
"version": "8.13.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.12.1",
"status": "affected",
"version": "8.12.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.12.0",
"status": "affected",
"version": "8.12.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.11.1",
"status": "affected",
"version": "8.11.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.11.0",
"status": "affected",
"version": "8.11.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.10.1",
"status": "affected",
"version": "8.10.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.10.0",
"status": "affected",
"version": "8.10.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.9.1",
"status": "affected",
"version": "8.9.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.9.0",
"status": "affected",
"version": "8.9.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.8.0",
"status": "affected",
"version": "8.8.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.7.1",
"status": "affected",
"version": "8.7.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.7.0",
"status": "affected",
"version": "8.7.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.6.0",
"status": "affected",
"version": "8.6.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.5.0",
"status": "affected",
"version": "8.5.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.4.0",
"status": "affected",
"version": "8.4.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.3.0",
"status": "affected",
"version": "8.3.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.2.1",
"status": "affected",
"version": "8.2.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.2.0",
"status": "affected",
"version": "8.2.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.1.2",
"status": "affected",
"version": "8.1.2",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.1.1",
"status": "affected",
"version": "8.1.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.1.0",
"status": "affected",
"version": "8.1.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.0.1",
"status": "affected",
"version": "8.0.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.0.0",
"status": "affected",
"version": "8.0.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.88.1",
"status": "affected",
"version": "7.88.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.88.0",
"status": "affected",
"version": "7.88.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.87.0",
"status": "affected",
"version": "7.87.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.86.0",
"status": "affected",
"version": "7.86.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.85.0",
"status": "affected",
"version": "7.85.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.84.0",
"status": "affected",
"version": "7.84.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.83.1",
"status": "affected",
"version": "7.83.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.83.0",
"status": "affected",
"version": "7.83.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.82.0",
"status": "affected",
"version": "7.82.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.81.0",
"status": "affected",
"version": "7.81.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.80.0",
"status": "affected",
"version": "7.80.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.79.1",
"status": "affected",
"version": "7.79.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.79.0",
"status": "affected",
"version": "7.79.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.78.0",
"status": "affected",
"version": "7.78.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.77.0",
"status": "affected",
"version": "7.77.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.76.1",
"status": "affected",
"version": "7.76.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.76.0",
"status": "affected",
"version": "7.76.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.75.0",
"status": "affected",
"version": "7.75.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.74.0",
"status": "affected",
"version": "7.74.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.73.0",
"status": "affected",
"version": "7.73.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.72.0",
"status": "affected",
"version": "7.72.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.71.1",
"status": "affected",
"version": "7.71.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.71.0",
"status": "affected",
"version": "7.71.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.70.0",
"status": "affected",
"version": "7.70.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.69.1",
"status": "affected",
"version": "7.69.1",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.69.0",
"status": "affected",
"version": "7.69.0",
"versionType": "semver"
}
]
}
],
"source": "2499f714-1537-4658-8207-48ae4bb9eae9"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "When a libcurl-based application performs transfers via `SCP://` or `SFTP://`\nand utilizes the `CURLOPT_SSH_KEYFUNCTION` callback, it may silently accept an\nuntrusted server. This vulnerability occurs when a server presents a host key\ntype that does not match the specific key type already recorded for that host\nin the `known_hosts` file. Instead of rejecting the mismatch, the callback\nmechanism fails to properly enforce the restriction, allowing the connection\nto succeed without warning and risking a potential man-in-the-middle attack."
}
],
"id": "CVE-2026-9547",
"lastModified": "2026-07-06T18:20:47.007",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "HIGH",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 7.4,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
"version": "3.1"
},
"exploitabilityScore": 2.2,
"impactScore": 5.2,
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-9547",
"options": [
{
"exploitation": "poc"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-07-06T16:47:32.456534Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-07-03T07:16:25.990",
"references": [
{
"source": "2499f714-1537-4658-8207-48ae4bb9eae9",
"url": "https://curl.se/docs/CVE-2026-9547.html"
},
{
"source": "2499f714-1537-4658-8207-48ae4bb9eae9",
"url": "https://curl.se/docs/CVE-2026-9547.json"
},
{
"source": "2499f714-1537-4658-8207-48ae4bb9eae9",
"url": "https://hackerone.com/reports/3751712"
},
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"url": "https://hackerone.com/reports/3751712"
}
],
"sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9",
"vulnStatus": "Awaiting Analysis"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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