Information disclosure in Curl
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.
Vulnerability class: Information Disclosure
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.007 (49.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 49.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.007 · change: +0.002
Affected products
Weakness classification (CWE)
References
- 2499f714-1537-4658-8207-48ae4bb9eae9 (Third Party Advisory)
- 2499f714-1537-4658-8207-48ae4bb9eae9 (Patch, Vendor Advisory)
- 2499f714-1537-4658-8207-48ae4bb9eae9 (Exploit, Third Party Advisory, Issue Tracking)
Frequently asked questions
- What is CVE-2026-9546?
- CVE-2026-9546 is a high-severity vulnerability in Curl, classified under Information Disclosure. CVSS score: 7.5/10. Published 2026-07-03.
- How severe is CVE-2026-9546?
- High severity. CVSS v3 base score is 7.5 out of 10.