Summary
djust: A template binding inherits a context safety grant it never earned (XSS)
A context safety grant was inherited by a template binding that never earned it, so rebinding a name the view had marked safe left the mark attached to the new, attacker-controlled value.
djust's context safety channel is keyed by name, not by value. Every bind copied the value and left the grant in place:
view marks p = mark_safe('<b>trusted</b>')
template {% with p=user_input %}{{ p }}{% endwith %}
djust '<img src=x onerror=alert(1)>' <- executes
django '<img src=x onerror=alert(1)>'
Affected binds
Eight distinct shapes were live. All are fixed in 1.1.2:
| shape | example |
|---|---|
{% with %} rebinding a marked name |
{% with p=hostile %}{{ p }}{% endwith %} |
{% with %} descendant of a rebound name |
{% with p=hostile %}{{ p.a }}{% endwith %} |
{% with %} binding over a marked name |
{% with q=hostile %}{{ q }}{% endwith %} |
{% for %} loop variable |
{% for p in hostiles %}{{ p }}{% endfor %} |
{% for %} descendant |
{% for p in hostiles %}{{ p.a }}{% endfor %} |
{% for %} tuple unpacking |
{% for k, v in rows %}{{ v }}{% endfor %} |
{% include … with %} |
{% include "c.html" with q=hostile %} |
| assign tags | {% … as x %} |
No filter chain and no |safe anywhere in the template is required. The precondition is that the application marked some value safe under a name that a template later rebinds, an ordinary pattern, since a view commonly marks trusted markup safe and templates commonly reuse short names such as p, item or row.
Workarounds
Before upgrading, avoid reusing a context name for both mark_safe'd content and untrusted input, and avoid rebinding such a name in {% with %}, {% for %}, {% include … with %} or an assign tag.
Credit
Found while preparing the 1.1.1 security release: the reproducer published in GHSA-9395-2g46-rj3f was run against the built 1.1.1 artifact before that advisory was published, and proved the class was still live. Publishing the original text would have reported this class as patched when it was not.
Impact
Stored or reflected XSS in any djust application that combines mark_safe (or any framework path that grants a context key safety) with a template that rebinds that name. Exploitation requires no unusual template construct.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Fixed in 1.1.2, and in 1.2.0 (main).
The rule is that a bind replaces the grant rather than inheriting one. It is stated that way deliberately: the originally reported defects pointed the opposite direction, a grant being lost across some binds, causing over-escaping, and fixing only the reported direction would have left this leak in place. Both directions are the same rule.
Not fixed in 1.1.2, and tracked for 1.2.0: two over-escaping cases where a grant fails to travel with a value that legitimately carries one ({% with body=post.text|linebreaks %}, and mark_safe reaching a template through dict.values / dict.items). Both escape more than Django rather than less, so neither is a leak.
Frequently Asked Questions
- What is GHSA-XJW9-38CR-6372? GHSA-XJW9-38CR-6372 is a high-severity cross-site scripting (XSS) vulnerability in djust (pip), affecting versions <= 1.1.1. It is fixed in 1.1.2. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- Which versions of djust are affected by GHSA-XJW9-38CR-6372? djust (pip) versions <= 1.1.1 is affected.
- Is there a fix for GHSA-XJW9-38CR-6372? Yes. GHSA-XJW9-38CR-6372 is fixed in 1.1.2. Upgrade to this version or later.
- Is GHSA-XJW9-38CR-6372 exploitable, and should I be worried? Whether GHSA-XJW9-38CR-6372 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-XJW9-38CR-6372 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-XJW9-38CR-6372? Upgrade
djustto 1.1.2 or later.