Improper Neutralization of Special Elements in Output Used by a Downstream Component in Caddy - CVE-2026-30852
Published: April 27, 2026
Vulnerability identifier: #VU128035
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-30852
CWE-ID: CWE-74
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Caddy
Affected software:
Caddy
Caddy
Detailed vulnerability description
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to improper neutralization of special elements in the vars_regexp matcher when processing user-controlled placeholder values. A remote attacker can send a specially crafted request header to disclose sensitive information.
Exploitation requires a configuration in which vars_regexp matches user-controlled input and the captured value is reflected in the response.
How to mitigate CVE-2026-30852
Install security update from vendor's website.