CVE-2026-54163
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…
Does this matter?
Lower severity and a low EPSS score (0.29%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 4.7 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N
- EPSS
- 0.29% probability · 21th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-79, CWE-113
- Source
- security-advisories@github.com
References
- https://github.com/github/secure_headers/commit/286a79dea80c6a9be4ca93e0f284c923cf77e539
- https://github.com/github/secure_headers/releases/tag/v7.3.0
- https://github.com/github/secure_headers/security/advisories/GHSA-rqq5-2gf9-4w4q
- https://github.com/github/secure_headers/security/advisories/GHSA-rqq5-2gf9-4w4q
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.