CVE-2026-9546 Affecting curl package, versions <8.21.0~rc2-1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.4% (33rd percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-CURL-17440294
  • published24 Jun 2026
  • disclosed3 Jul 2026

Introduced: 24 Jun 2026

CVE-2026-9546  (opens in a new tab)

How to fix?

Upgrade Debian:unstable curl to version 8.21.0~rc2-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream curl package and not the curl package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1