CVE-2026-86414

An HTTP proxy can trick libcurl into sending the origin's credentials (Basic password, or a Negotiate/Kerberos ticket) to the proxy itself, by answering the `CONNECT` tunnel request with 401 `WWW-Authenticate:` instead of the expected 407 `Proxy-Authenticate:`.

CVSS v3 9.1 CRITICAL

9.1^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://curl.se/docs/CVE-2026-86414.html
https://curl.se/docs/CVE-2026-86414.json
https://hackerone.com/reports/3993566
https://hackerone.com/reports/3993566

Configurations

No configuration.

History

30 Oct 2026, 12:16

Type	Values Removed	Values Added
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 9.1
CWE		CWE-201
References	~~() https://hackerone.com/reports/3993566 -~~	() https://hackerone.com/reports/3993566 -

20 Oct 2026, 21:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-20 21:17

Updated : 2026-10-30 12:16

NVD link : CVE-2026-86414

Mitre link : CVE-2026-86414

CVE.ORG link : CVE-2026-86414

JSON object : View

Products Affected

No product.

CWE

CWE-201

Insertion of Sensitive Information Into Sent Data

{"id": "CVE-2026-86414", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-86414", "role": "CISA Coordinator", "options": [{"exploitation": "poc"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-10-30T11:46:48.401587Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 9.1, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.2, "exploitabilityScore": 3.9}]}, "affected": [{"source": "2499f714-1537-4658-8207-48ae4bb9eae9", "affectedData": [{"vendor": "curl", "product": "curl", "versions": [{"status": "affected", 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"lessThanOrEqual": "7.11.0"}, {"status": "affected", "version": "7.10.8", "versionType": "semver", "lessThanOrEqual": "7.10.8"}], "defaultStatus": "unaffected"}]}], "published": "2026-10-20T21:17:19.947", "references": [{"url": "https://curl.se/docs/CVE-2026-86414.html", "source": "2499f714-1537-4658-8207-48ae4bb9eae9"}, {"url": "https://curl.se/docs/CVE-2026-86414.json", "source": "2499f714-1537-4658-8207-48ae4bb9eae9"}, {"url": "https://hackerone.com/reports/3993566", "source": "2499f714-1537-4658-8207-48ae4bb9eae9"}, {"url": "https://hackerone.com/reports/3993566", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Awaiting Analysis", "weaknesses": [{"type": "Secondary", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "description": [{"lang": "en", "value": "CWE-201"}]}], "descriptions": [{"lang": "en", "value": "An HTTP proxy can trick libcurl into sending the origin's credentials (Basic\npassword, or a Negotiate/Kerberos ticket) to the proxy itself, by answering\nthe `CONNECT` tunnel request with 401 `WWW-Authenticate:` instead of the\nexpected 407 `Proxy-Authenticate:`."}], "lastModified": "2026-10-30T12:16:45.243", "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9"}