CVE-2026-54163: secure_headers manages application of security headers with many safe defaults. Prior to 7.3.0, secure_headers builds the Content-Security-Policy valu...

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.

Metrics

CVSS 3.1

4.7/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

0.29%

20.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
github	secure_headers	< 7.3.0

References

Timeline

Published: Jul 17, 2026
Last Modified: Jul 23, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-54163?

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.

How severe is CVE-2026-54163?

CVE-2026-54163 has a CVSS score of 4.7/10 (MEDIUM severity). The EPSS model estimates a 0.29% probability of exploitation in the next 30 days.

How do I fix CVE-2026-54163?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

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