CVE-2026-9546
Last modified
CVE-2026-9546 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.49% chance of exploitation in the next 30 days.
Description
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Haxx | Curl | >= 8.18.0, < 8.21.0 |
References
- https://curl.se/docs/CVE-2026-9546.htmlPatch, Vendor Advisory
- https://curl.se/docs/CVE-2026-9546.jsonThird Party Advisory
- https://hackerone.com/reports/3754343Exploit, Issue Tracking, Third Party Advisory
- https://hackerone.com/reports/3754343Exploit, Issue Tracking, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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