Reference page — cumulative record through Tuesday, October 6, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-9546

CVE-2026-9546HIGH

curl curl — sending old referer

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  U  H  N  N    7.5   .0065   49.5     —

AFFECTED
  Product  Versions                                    Fixed
  curl     8.18.0 –                                    —
  curl     2cb868242dc2ac9cd52ee64987ef51d5964a56f9 –  —
  curl     8.20.0 –                                    —

TIMELINE
  May 26  Reserved by curl
  Jul 3   EXPLOIT PUBLISHED — CVE-2026-9546 (curl). Public exploit reference added.
  Jul 3   Published (CNA: curl)
  Sep 15  EXPLOIT PUBLISHED — CVE-2026-9546 (curl). Public exploit reference added.

CWE-200 · CNA: curl · CVSS v3.1 · 3 references · NVD status: Modified

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.

Lifecycle

Complete event history — 4 events, chronological
Date	Event	Detail
May 26, 2026	Reserved	Reserved by curl
July 3, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-9546 (curl). Public exploit reference added.
July 3, 2026	Published	Published (CNA: curl)
September 15, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-9546 (curl). Public exploit reference added.

Affected

Affected products and packages — 3 rows
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
curl	curl	—	8.18.0	—
curl	curl	—	2cb868242dc2ac9cd52ee64987ef51d5964a56f9	—
curl	curl	—	8.20.0	—

Weaknesses

CWE-200

References (3)

https://curl.se/docs/CVE-2026-9546.html [Patch, Vendor Advisory]
https://curl.se/docs/CVE-2026-9546.json [Third Party Advisory]
https://hackerone.com/reports/3754343 [Exploit, Issue Tracking, Third Party Advisory]

Authoritative record: CVE-2026-9546 at cve.org

Vendors: curl

Weaknesses: CWE-200

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-9546 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Tuesday, October 6, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.