vulnerability / NVI-00016171 / Revision 1
DOMPurify: Permanent `ALLOWED_ATTR` pollution via `setConfig()` bypassing the hook clone-guard (incomplete fix of the 3.4.7 hook-pollution patch)
GitHub lists this reviewed advisory for dompurify. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
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02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
dompurify
source listed<= 3.4.10
## Summary DOMPurify 3.4.7 shipped a security fix ("permanent hook pollution") that makes a registered `uponSanitizeAttribute` hook's mutation of `data.allowedAttributes` **non-persistent** — so allowing an attribute for one element does not leak into later `sanitize()` calls. The fix clones `ALLOWED_ATTR` inside `_parseConfig`. That guard is **silently bypassed whenever the application uses the persistent-config API `DOMPurify.setConfig()`.** `setConfig()` sets the module flag `SET_CONFIG = true`, which causes `sanitize()` to **skip `_parseConfig` entirely** — and the clone-guard lives inside `_parseConfig`. The hook is then handed the **live, shared `ALLOWED_ATTR` object**; any `data.allowedAttributes[name] = true` it writes mutates that shared object **permanently**, for the lifetime of the DOMPurify instance, across every subsequent call, and across **all** elements. If an application uses `setConfig()` together with an `uponSanitizeAttribute` hook that conditionally allows a dangerous attribute (`onerror`, `onclick`, `onmouseover`, `srcdoc`, `formaction`, …) for "trusted" elements, then **one trusted render permanently allows that attribute on untrusted, attacker-controlled
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
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04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-cmwh-pvxp-8882 ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
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