FKIE_CVE-2026-4873
Vulnerability from fkie_nvd - Published: 2026-05-13 13:01 - Updated: 2026-09-15 07:16
Severity
Summary
A vulnerability exists where a connection requiring TLS incorrectly reuses an
existing unencrypted connection from the same connection pool. If an initial
transfer is made in clear-text (via IMAP, SMTP, or POP3), a subsequent request
to that same host bypasses the TLS requirement and instead transmit data
unencrypted.
References
| URL | Tags | ||
|---|---|---|---|
| 2499f714-1537-4658-8207-48ae4bb9eae9 | https://curl.se/docs/CVE-2026-4873.html | Patch, Vendor Advisory | |
| 2499f714-1537-4658-8207-48ae4bb9eae9 | https://curl.se/docs/CVE-2026-4873.json | Vendor Advisory | |
| 2499f714-1537-4658-8207-48ae4bb9eae9 | https://hackerone.com/reports/3621851 | Exploit, Issue Tracking, Third Party Advisory | |
| af854a3a-2127-422b-91ae-364da2661108 | http://www.openwall.com/lists/oss-security/2026/04/29/7 | Mailing List, Patch, Third Party Advisory |
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "curl",
"vendor": "curl",
"versions": [
{
"lessThan": "8.14.2",
"status": "affected",
"version": "7.20.0",
"versionType": "semver"
},
{
"lessThan": "8.16.1",
"status": "affected",
"version": "8.15.0",
"versionType": "semver"
},
{
"lessThan": "8.20.0",
"status": "affected",
"version": "8.17.0",
"versionType": "semver"
}
]
},
{
"defaultStatus": "unaffected",
"product": "curl",
"repo": "https://github.com/curl/curl.git",
"vendor": "curl",
"versions": [
{
"lessThan": "507e7be573b0a76fca597b75ff7cb27a66e7d865",
"status": "affected",
"version": "ec3bb8f727405642a471b4b1b9eb0118fc003104",
"versionType": "git"
}
]
},
{
"defaultStatus": "unaffected",
"product": "curl",
"vendor": "curl",
"versions": [
{
"status": "affected",
"version": "8.19.0"
},
{
"status": "affected",
"version": "8.18.0"
},
{
"status": "affected",
"version": "8.17.0"
},
{
"status": "affected",
"version": "8.16.0"
},
{
"status": "affected",
"version": "8.15.0"
},
{
"status": "affected",
"version": "8.14.1"
},
{
"status": "affected",
"version": "8.14.0"
},
{
"status": "affected",
"version": "8.13.0"
},
{
"status": "affected",
"version": "8.12.1"
},
{
"status": "affected",
"version": "8.12.0"
},
{
"status": "affected",
"version": "8.11.1"
},
{
"status": "affected",
"version": "8.11.0"
},
{
"status": "affected",
"version": "8.10.1"
},
{
"status": "affected",
"version": "8.10.0"
},
{
"status": "affected",
"version": "8.9.1"
},
{
"status": "affected",
"version": "8.9.0"
},
{
"status": "affected",
"version": "8.8.0"
},
{
"status": "affected",
"version": "8.7.1"
},
{
"status": "affected",
"version": "8.7.0"
},
{
"status": "affected",
"version": "8.6.0"
},
{
"status": "affected",
"version": "8.5.0"
},
{
"status": "affected",
"version": "8.4.0"
},
{
"status": "affected",
"version": "8.3.0"
},
{
"status": "affected",
"version": "8.2.1"
},
{
"status": "affected",
"version": "8.2.0"
},
{
"status": "affected",
"version": "8.1.2"
},
{
"status": "affected",
"version": "8.1.1"
},
{
"status": "affected",
"version": "8.1.0"
},
{
"status": "affected",
"version": "8.0.1"
},
{
"status": "affected",
"version": "8.0.0"
},
{
"status": "affected",
"version": "7.88.1"
},
{
"status": "affected",
"version": "7.88.0"
},
{
"status": "affected",
"version": "7.87.0"
},
{
"status": "affected",
"version": "7.86.0"
},
{
"status": "affected",
"version": "7.85.0"
},
{
"status": "affected",
"version": "7.84.0"
},
{
"status": "affected",
"version": "7.83.1"
},
{
"status": "affected",
"version": "7.83.0"
},
{
"status": "affected",
"version": "7.82.0"
},
{
"status": "affected",
"version": "7.81.0"
},
{
"status": "affected",
"version": "7.80.0"
},
{
"status": "affected",
"version": "7.79.1"
},
{
"status": "affected",
"version": "7.79.0"
},
{
"status": "affected",
"version": "7.78.0"
},
{
"status": "affected",
"version": "7.77.0"
},
{
"status": "affected",
"version": "7.76.1"
},
{
"status": "affected",
"version": "7.76.0"
},
{
"status": "affected",
"version": "7.75.0"
},
{
"status": "affected",
"version": "7.74.0"
},
{
"status": "affected",
"version": "7.73.0"
},
{
"status": "affected",
"version": "7.72.0"
},
{
"status": "affected",
"version": "7.71.1"
},
{
"status": "affected",
"version": "7.71.0"
},
{
"status": "affected",
"version": "7.70.0"
},
{
"status": "affected",
"version": "7.69.1"
},
{
"status": "affected",
"version": "7.69.0"
},
{
"status": "affected",
"version": "7.68.0"
},
{
"status": "affected",
"version": "7.67.0"
},
{
"status": "affected",
"version": "7.66.0"
},
{
"status": "affected",
"version": "7.65.3"
},
{
"status": "affected",
"version": "7.65.2"
},
{
"status": "affected",
"version": "7.65.1"
},
{
"status": "affected",
"version": "7.65.0"
},
{
"status": "affected",
"version": "7.64.1"
},
{
"status": "affected",
"version": "7.64.0"
},
{
"status": "affected",
"version": "7.63.0"
},
{
"status": "affected",
"version": "7.62.0"
},
{
"status": "affected",
"version": "7.61.1"
},
{
"status": "affected",
"version": "7.61.0"
},
{
"status": "affected",
"version": "7.60.0"
},
{
"status": "affected",
"version": "7.59.0"
},
{
"status": "affected",
"version": "7.58.0"
},
{
"status": "affected",
"version": "7.57.0"
},
{
"status": "affected",
"version": "7.56.1"
},
{
"status": "affected",
"version": "7.56.0"
},
{
"status": "affected",
"version": "7.55.1"
},
{
"status": "affected",
"version": "7.55.0"
},
{
"status": "affected",
"version": "7.54.1"
},
{
"status": "affected",
"version": "7.54.0"
},
{
"status": "affected",
"version": "7.53.1"
},
{
"status": "affected",
"version": "7.53.0"
},
{
"status": "affected",
"version": "7.52.1"
},
{
"status": "affected",
"version": "7.52.0"
},
{
"status": "affected",
"version": "7.51.0"
},
{
"status": "affected",
"version": "7.50.3"
},
{
"status": "affected",
"version": "7.50.2"
},
{
"status": "affected",
"version": "7.50.1"
},
{
"status": "affected",
"version": "7.50.0"
},
{
"status": "affected",
"version": "7.49.1"
},
{
"status": "affected",
"version": "7.49.0"
},
{
"status": "affected",
"version": "7.48.0"
},
{
"status": "affected",
"version": "7.47.1"
},
{
"status": "affected",
"version": "7.47.0"
},
{
"status": "affected",
"version": "7.46.0"
},
{
"status": "affected",
"version": "7.45.0"
},
{
"status": "affected",
"version": "7.44.0"
},
{
"status": "affected",
"version": "7.43.0"
},
{
"status": "affected",
"version": "7.42.1"
},
{
"status": "affected",
"version": "7.42.0"
},
{
"status": "affected",
"version": "7.41.0"
},
{
"status": "affected",
"version": "7.40.0"
},
{
"status": "affected",
"version": "7.39.0"
},
{
"status": "affected",
"version": "7.38.0"
},
{
"status": "affected",
"version": "7.37.1"
},
{
"status": "affected",
"version": "7.37.0"
},
{
"status": "affected",
"version": "7.36.0"
},
{
"status": "affected",
"version": "7.35.0"
},
{
"status": "affected",
"version": "7.34.0"
},
{
"status": "affected",
"version": "7.33.0"
},
{
"status": "affected",
"version": "7.32.0"
},
{
"status": "affected",
"version": "7.31.0"
},
{
"status": "affected",
"version": "7.30.0"
},
{
"status": "affected",
"version": "7.29.0"
},
{
"status": "affected",
"version": "7.28.1"
},
{
"status": "affected",
"version": "7.28.0"
},
{
"status": "affected",
"version": "7.27.0"
},
{
"status": "affected",
"version": "7.26.0"
},
{
"status": "affected",
"version": "7.25.0"
},
{
"status": "affected",
"version": "7.24.0"
},
{
"status": "affected",
"version": "7.23.1"
},
{
"status": "affected",
"version": "7.23.0"
},
{
"status": "affected",
"version": "7.22.0"
},
{
"status": "affected",
"version": "7.21.7"
},
{
"status": "affected",
"version": "7.21.6"
},
{
"status": "affected",
"version": "7.21.5"
},
{
"status": "affected",
"version": "7.21.4"
},
{
"status": "affected",
"version": "7.21.3"
},
{
"status": "affected",
"version": "7.21.2"
},
{
"status": "affected",
"version": "7.21.1"
},
{
"status": "affected",
"version": "7.21.0"
},
{
"status": "affected",
"version": "7.20.1"
},
{
"status": "affected",
"version": "7.20.0"
}
]
}
],
"source": "2499f714-1537-4658-8207-48ae4bb9eae9"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*",
"matchCriteriaId": "50906082-180F-4E8B-A3E5-AC2C14B54B89",
"versionEndExcluding": "8.20.0",
"versionStartIncluding": "7.20.0",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "A vulnerability exists where a connection requiring TLS incorrectly reuses an\nexisting unencrypted connection from the same connection pool. If an initial\ntransfer is made in clear-text (via IMAP, SMTP, or POP3), a subsequent request\nto that same host bypasses the TLS requirement and instead transmit data\nunencrypted."
}
],
"id": "CVE-2026-4873",
"lastModified": "2026-09-15T07:16:28.367",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "HIGH",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 5.9,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "HIGH",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
"version": "3.1"
},
"exploitabilityScore": 2.2,
"impactScore": 3.6,
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-4873",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-05-13T19:29:14.521822Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-05-13T13:01:55.893",
"references": [
{
"source": "2499f714-1537-4658-8207-48ae4bb9eae9",
"tags": [
"Patch",
"Vendor Advisory"
],
"url": "https://curl.se/docs/CVE-2026-4873.html"
},
{
"source": "2499f714-1537-4658-8207-48ae4bb9eae9",
"tags": [
"Vendor Advisory"
],
"url": "https://curl.se/docs/CVE-2026-4873.json"
},
{
"source": "2499f714-1537-4658-8207-48ae4bb9eae9",
"tags": [
"Exploit",
"Issue Tracking",
"Third Party Advisory"
],
"url": "https://hackerone.com/reports/3621851"
},
{
"source": "af854a3a-2127-422b-91ae-364da2661108",
"tags": [
"Mailing List",
"Patch",
"Third Party Advisory"
],
"url": "http://www.openwall.com/lists/oss-security/2026/04/29/7"
}
],
"sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9",
"vulnStatus": "Modified",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-319"
}
],
"source": "2499f714-1537-4658-8207-48ae4bb9eae9",
"type": "Secondary"
},
{
"description": [
{
"lang": "en",
"value": "CWE-295"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
},
{
"description": [
{
"lang": "en",
"value": "CWE-319"
}
],
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
]
}
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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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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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