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Potential XSS vulnerability in Action View

Moderate
georgeclaghorn published GHSA-cfjv-5498-mph5 Sep 11, 2020

Package

bundler actionview (Rubygems)

Affected versions

All

Patched versions

6.0.3.3, 5.2.4.4

Description

There is a potential Cross-Site Scripting (XSS) vulnerability in Action View's translation helpers. Views that allow the user to control the default (not found) value of the t and translate helpers could be susceptible to XSS attacks.

Impact

When an HTML-unsafe string is passed as the default for a missing translation key named html or ending in _html, the default string is incorrectly marked as HTML-safe and not escaped. Vulnerable code may look like the following examples:

<%# The welcome_html translation is not defined for the current locale: %>
<%= t("welcome_html", default: untrusted_user_controlled_string) %>

<%# Neither the title.html translation nor the missing.html translation is defined for the current locale: %>
<%= t("title.html", default: [:"missing.html", untrusted_user_controlled_string]) %>

Patches

Patched Rails versions, 6.0.3.3 and 5.2.4.4, are available from the normal locations.

The patches have also been applied to the master, 6-0-stable, and 5-2-stable branches on GitHub. If you track any of these branches, you should update to the latest.

To aid users who aren’t able to upgrade immediately, we’ve provided patches for the two supported release series. They are in git-am format and consist of a single changeset.

Please note that only the 5.2 and 6.0 release series are currently supported. Users of earlier, unsupported releases are advised to update as soon as possible, as we cannot provide security fixes for unsupported releases.

Workarounds

Impacted users who can’t upgrade to a patched Rails version can avoid this issue by manually escaping default translations with the html_escape helper (aliased as h):

<%= t("welcome_html", default: h(untrusted_user_controlled_string)) %>

Severity

Moderate

CVE ID

CVE-2020-15169

Weaknesses

No CWEs