CVE-2026-54163

secureheaders manages application of security headers with many safe defaults. Prior to 7.3.0, secureheaders builds the Content-Security-Policy value by stitching directives with ; separators, and buildsandboxlistdirective, buildmediatypelistdirective, and buildreporttodirective interpolate caller-supplied strings without scrubbing ;, \r, or \n. When untrusted input reaches SecureHeaders.overridecontentsecuritypolicydirectives or append APIs for :sandbox, :plugintypes, or :reportto, an attacker can inject a CSP directive such as script-src 'unsafe-inline' * before the legitimate script-src, enabling XSS reachability through these sinks or CSP report exfiltration. This issue is fixed in version 7.3.0.