sending old referer

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-9546
StatePUBLISHED
Assignercurl
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-03 07:16:25 UTC
Updated2026-07-07 14:53:26 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

Primary CVSS: v3.1 7.5 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS: 0.006520000 probability, percentile 0.468630000 (date 2026-07-09)

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

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Haxx Curl All All All All

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
hackerone.com/reports/3754343 134c704f-9b21-4f2e-91b3-4a467353bcc0 hackerone.com Exploit, Issue Tracking, Third Party Advisory
curl.se/docs/CVE-2026-9546.html 2499f714-1537-4658-8207-48ae4bb9eae9 curl.se Patch, Vendor Advisory
curl.se/docs/CVE-2026-9546.json 2499f714-1537-4658-8207-48ae4bb9eae9 curl.se Third Party Advisory
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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