Vulnerability · Published Jul 3, 2026 · Assigned by curl
CVE-2026-9546sending old referer
High 7.5
In plain English
A high-severity information exposure in curl from curl. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 51% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | curl | 8.22.0-r0 | ALPINE-CVE-2026-9546 |
| Alpine:v3.24 | curl | 8.21.0-r0 | ALPINE-CVE-2026-9546 |
| Debian:14 | curl | 8.21.0~rc2-1 | DEBIAN-CVE-2026-9546 |
| Ubuntu:26.04:LTS | curl | no fix listed | UBUNTU-CVE-2026-9546 |
Affected products (as reported)
Weakness: CWE-200 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N