Vulnerability · Published Jul 17, 2026 · Assigned by GitHub_M
CVE-2026-54163secure_headers: CSP directive injection via sandbox, plugin_types, and report_to when given untrusted input
Medium 4.7
In plain English
A medium-severity cross-site scripting in secure_headers from github. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | ruby-secure-headers | no fix listed | DEBIAN-CVE-2026-54163 |
| Debian:13 | ruby-secure-headers | no fix listed | DEBIAN-CVE-2026-54163 |
| Debian:14 | ruby-secure-headers | 7.3.0-1 | DEBIAN-CVE-2026-54163 |
| RubyGems | secure_headers | 7.3.0 | GHSA-rqq5-2gf9-4w4q |
| Ubuntu:22.04:LTS | ruby-secure-headers | no fix listed | UBUNTU-CVE-2026-54163 |
| Ubuntu:24.04:LTS | ruby-secure-headers | no fix listed | UBUNTU-CVE-2026-54163 |
| Ubuntu:26.04:LTS | ruby-secure-headers | no fix listed | UBUNTU-CVE-2026-54163 |
| Ubuntu:26.10 | ruby-secure-headers | no fix listed | UBUNTU-CVE-2026-54163 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| github | secure_headers | < 7.3.0 |
Weakness: CWE-79, CWE-113 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N