high7.5
CVE-2026-9546
A vulnerability in libcurl caused the HTTP `Referer:` header to persist even when explicitly cleared.
Impact
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.
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Haxx | Curl | from 8.18.0 before 8.21.0 |