CVE-2026-9546

A vulnerability in libcurl caused the HTTP `Referer:` header to persist even when explicitly cleared. While the documentation states that passing NULL to `CURLOPT_REFERER` suppresses the header, the option failed to clear the internal state. As a result the previous referrer string was erroneously reused and sent in subsequent requests, potentially leaking sensitive information to unintended servers.

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 HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://curl.se/docs/CVE-2026-9546.html	Patch Vendor Advisory
https://curl.se/docs/CVE-2026-9546.json	Third Party Advisory
https://hackerone.com/reports/3754343	Exploit Issue Tracking Third Party Advisory
https://hackerone.com/reports/3754343	Exploit Issue Tracking Third Party Advisory

Configurations

Configuration 1 (hide)

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

History

07 Jul 2026, 14:53

Type	Values Removed	Values Added
References	~~() https://curl.se/docs/CVE-2026-9546.html -~~	() https://curl.se/docs/CVE-2026-9546.html - Patch, Vendor Advisory
References	~~() https://curl.se/docs/CVE-2026-9546.json -~~	() https://curl.se/docs/CVE-2026-9546.json - Third Party Advisory
References	~~() https://hackerone.com/reports/3754343 -~~	() https://hackerone.com/reports/3754343 - Exploit, Issue Tracking, Third Party Advisory
CWE		NVD-CWE-noinfo
CPE		cpe:2.3:a:haxx:curl::::::::
First Time		Haxx curl Haxx

06 Jul 2026, 18:16

Type	Values Removed	Values Added
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 7.5
References	~~() https://hackerone.com/reports/3754343 -~~	() https://hackerone.com/reports/3754343 -

03 Jul 2026, 07:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-07-03 07:16

Updated : 2026-07-07 14:53

NVD link : CVE-2026-9546

Mitre link : CVE-2026-9546

CVE.ORG link : CVE-2026-9546

JSON object : View

Products Affected

haxx

curl

CWE

NVD-CWE-noinfo

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