dotvitals

The policy leaves plugins or the base URL unrestricted

LowConfirmedQuick winweb.security-headers.csp-no-object-or-base

What this check looks for

Two easily-forgotten parts of the policy are unset. Both are used to work around otherwise strict policies.

Why it matters

base-uri is the one most often missed: without it, an injected <base> tag can silently redirect every relative script URL on the page to an attacker's server, defeating a policy that otherwise only allows your own origin.

When the check passes, your report says: “The policy restricts plugins and the page's base URL”.

What it costs your score

When this check fails it removes 4 points from your Web security score, before the status, confidence and repeat multipliers are applied. Web security carries a weight of 8 in the overall score.

It shares the web-security.csp family ceiling of 30 points: however many findings that family produces, together they cannot remove more than that from Web security. One underlying problem showing up in several places is still one problem.

Severity
low
Default confidence
confirmed
Status when triggered
warn
Deduction
4 points
Family cap
web-security.csp · 30
Category
Web security
Module
Web security headers
Fix owned by
user
In the ruleset since
2026.09

How the whole score is calculated

How to fix it

Add object-src 'none' and base-uri 'none'.

base-uri has no default; without it a single injected tag can redirect every script on the page.

  1. Append object-src 'none'; base-uri 'none' to the policy.

  2. Use base-uri 'self' instead if the site genuinely sets a <base> tag.

How to confirm it worked

  • curl -sSI https://‹host›/ | grep -i content-security-policy

The configuration to publish
Content-Security-Policy: ...; object-src 'none'; base-uri 'none'

A named slot like ‹domain› — and the braces left in the configuration below — is filled in with your own values when this rule appears on a report.

Remediation by platform

nginx
add_header Content-Security-Policy "default-src 'self'; object-src 'none'; base-uri 'none'" always;
Apache
<IfModule mod_headers.c>
	Header always set Content-Security-Policy "default-src 'self'; object-src 'none'; base-uri 'none'"
</IfModule>
Caddy
header {
	Content-Security-Policy "default-src 'self'; object-src 'none'; base-uri 'none'"
}
Cloudflare
Rules → Overview → Create rule → Response Header Transform Rule → Set static → Content-Security-Policy = default-src 'self'; object-src 'none'; base-uri 'none'
(Dashboard path as at 2026-09; Cloudflare reorganised these pages and may again.)

  • The always flag matters: without it nginx omits the header on error responses, which are exactly the ones an attacker aims for. Note also that any add_header in a location block discards every add_header inherited from the server block.

  • Shown because the response identified Apache. Put it in the virtual host rather than .htaccess: .htaccess is re-read on every request, and Header always set there runs too late for responses the server generates itself.

  • A Transform Rule adds the header at Cloudflare's edge, so it applies only to responses that reach visitors through Cloudflare. An origin that is reachable directly — by IP, or through a DNS record that is not proxied — still serves the response measured here without it. Setting it at the origin covers both paths.

Technical detail

‹detail›

Both are cheap to set and neither breaks anything on a normal site: object-src 'none' disables plugin content, which no current browser supports anyway, and base-uri 'none' stops the <base> redirection trick. Neither falls back to default-src in a way that helps — base-uri has no fallback at all.

Standards and references

Test this on your domain

Run the check that produces this finding, on its own, against any domain.

Open the web security headers checkerBuild the fix

Other web security headers checks