| Name | CVE-2026-9546 |
| 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. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|
| curl (PTS) | bullseye | 7.74.0-1.3+deb11u13 | fixed |
| bullseye (security) | 7.74.0-1.3+deb11u16 | fixed |
| bookworm | 7.88.1-10+deb12u15 | fixed |
| bookworm (security) | 7.88.1-10+deb12u5 | fixed |
| trixie | 8.14.1-2+deb13u4 | fixed |
| forky | 8.20.0-5 | vulnerable |
| sid | 8.21.0-2 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|
| curl | source | bullseye | (not affected) | | | |
| curl | source | bookworm | (not affected) | | | |
| curl | source | trixie | (not affected) | | | |
| curl | source | (unstable) | 8.21.0~rc2-1 | | | |
Notes
[trixie] - curl <not-affected> (Vulnerable code not present)
[bookworm] - curl <not-affected> (Vulnerable code not present)
[bullseye] - curl <not-affected> (Vulnerable code not present)
https://curl.se/docs/CVE-2026-9546.html
Introduced with: https://github.com/curl/curl/commit/2cb868242dc2ac9cd52ee64987ef51d5964a56f9 (curl-8_18_0)
Fixed by: https://github.com/curl/curl/commit/862e8a74a84478d82973471b4f49dc2746c1780e (rc-8_21_0-1, curl-8_21_0)