CVE-2026-54163
MEDIUMDescription
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 to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 21% of all known CVEs.
References
Related Vulnerabilities
Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2018-12998 | Medium | 6.1 | 99% | - | - |
| CVE-2020-11022 | Medium | 6.9 | 99% | - | Fix |
| CVE-2019-3929 | Critical | 9.8 | 99% | KEV | Fix |
| CVE-2020-9496 | Medium | 6.1 | 99% | - | - |
| CVE-2023-28341 | Medium | 6.1 | 99% | - | Fix |
| CVE-2021-25299 | Medium | 6.1 | 98% | - | - |
Common questions
How do I fix CVE-2026-54163?
Upgrade ruby-secure-headers on debian unstable to 7.3.0-1 or later.
Is CVE-2026-54163 being actively exploited?
Not that we know of. CVE-2026-54163 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.29% is the estimated probability that it will be exploited in the next 30 days. That is higher than 21% of all scored CVEs.
How severe is CVE-2026-54163?
CVE-2026-54163 has a CVSS v3 base score of 4.7, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-54163 affect?
Published advisories record a fix for ruby-secure-headers (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-23.