{"id":"CVE-2026-54163","aliases":["GHSA-rqq5-2gf9-4w4q"],"url":"https://o3.security/vulnerability/CVE-2026-54163","summary":"secure_headers: CSP directive injection via sandbox, plugin_types, and report_to when given untrusted input","details":"secure_headers manages application of security headers with many safe defaults. Prior to 7.3.0, secure_headers builds the Content-Security-Policy value by stitching directives with ; separators, and build_sandbox_list_directive, build_media_type_list_directive, and build_report_to_directive interpolate caller-supplied strings without scrubbing ;, \\r, or \\n. When untrusted input reaches SecureHeaders.override_content_security_policy_directives or append APIs for :sandbox, :plugin_types, or :report_to, 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.","published":"2026-07-17T20:19:18.186Z","modified":"2026-08-12T03:51:39.237780051Z","cvss":{"score":4.7,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N"},"epss":{"score":0.00286,"percentile":0.20834,"asOf":"2026-09-08"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"RubyGems","name":"secure_headers","fixedVersion":"7.3.0"}],"fix":{"url":"https://github.com/github/secure_headers/commit/286a79dea80c6a9be4ca93e0f284c923cf77e539","label":"github/secure_headers@286a79d"},"references":[{"type":"WEB","url":"https://github.com/github/secure_headers/releases/tag/v7.3.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54163.json"},{"type":"ADVISORY","url":"https://github.com/github/secure_headers/security/advisories/GHSA-rqq5-2gf9-4w4q"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54163"},{"type":"FIX","url":"https://github.com/github/secure_headers/commit/286a79dea80c6a9be4ca93e0f284c923cf77e539"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:39.237780051Z"}}