CVE-2026-6276

Using libcurl, when a custom `Host:` header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom `Host:` header set, the second request would use stale information and pass on cookies meant for the first host in the second request. Leak them.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://curl.se/docs/CVE-2026-6276.html	Patch Vendor Advisory
https://curl.se/docs/CVE-2026-6276.json	Product
https://hackerone.com/reports/3671818	Exploit Issue Tracking Third Party Advisory
http://www.openwall.com/lists/oss-security/2026/04/29/13	Mailing List Third Party Advisory
https://hackerone.com/reports/3671818	Exploit Issue Tracking Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-05-13 13:01

Updated : 2026-09-15 07:16

NVD link : CVE-2026-6276

Mitre link : CVE-2026-6276

CVE.ORG link : CVE-2026-6276

JSON object : View

Products Affected

haxx

curl

CWE

CWE-346

Origin Validation Error

CWE-319

Cleartext Transmission of Sensitive Information

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Leak them."}], "lastModified": "2026-09-15T07:16:29.343", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "4F8139D4-8C72-4D4D-BD15-A64E8818AED1", "versionEndExcluding": "8.20.0", "versionStartIncluding": "7.71.0"}], "operator": "OR"}]}], "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9"}