sending old referer

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Summary

CVECVE-2026-9546
StatePUBLISHED
Assignercurl
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-03 07:16:25 UTC
Updated2026-07-03 07:16:25 UTC
DescriptionA 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.

Risk And Classification

Problem Types: CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Curl Curl affected 8.20.0 8.20.0 semver Not specified
CNA Curl Curl affected 8.19.0 8.19.0 semver Not specified
CNA Curl Curl affected 8.18.0 8.18.0 semver Not specified

References

ReferenceSourceLinkTags
curl.se/docs/CVE-2026-9546.html 2499f714-1537-4658-8207-48ae4bb9eae9 curl.se
hackerone.com/reports/3754343 2499f714-1537-4658-8207-48ae4bb9eae9 hackerone.com
curl.se/docs/CVE-2026-9546.json 2499f714-1537-4658-8207-48ae4bb9eae9 curl.se
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: renjian on hackerone (en)

CNA: Daniel Stenberg (en)

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