# CVE-2026-65898: DOMPurify before 3.4.11 Permanent Attribute Allowlist Pollution via setConfig

> Attackers can exploit a DOMPurify configuration flaw to permanently pollute attribute allowlists, enabling stored XSS via event handlers.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 23 Jul 2026
- **Updated:** 23 Jul 2026
- **Also known as:** CLEANSTART-2026-BB38451, CLEANSTART-2026-IE01386, CLSA-2026-1784596280, CLSA-2026-1784596304, CLSA-2026-1784596347, CLSA-2026-1784682972, DEBIAN-CVE-2026-65898, ECHO-37cc-ac1b-a55e, GHSA-cmwh-pvxp-8882, MINI-28gw-gvfx-pqvh, MINI-6gqj-4g9p-v4gw, MINI-78j7-6whh-w49j, MINI-7crh-jxrq-739c, MINI-7j2x-78wf-39jf, MINI-7xmp-95pv-ghgx, MINI-cj63-67wm-84vh, MINI-h7x5-h6q6-pff5, MINI-jw3g-xjx6-6jgq, MINI-p3rp-23mw-3qjf, MINI-ph5c-c3hw-f675, MINI-qc8j-4mgp-8j2v, MINI-vr74-jpr6-jrgc, MINI-wcw3-9g5h-6vwr, MINI-wx3p-vf25-r9w9, MINI-x47h-qhpj-qfpg, MINI-x6vf-rjm2-vq5v, MINI-xhp8-5fx3-566m, ROOT-APP-NPM-CVE-2026-65898, ROOT-APP-NPM-GHSA-cmwh-pvxp-8882, UBUNTU-CVE-2026-65898

## What is CVE-2026-65898?

CVE-2026-65898 is a medium-severity cross-site scripting vulnerability in cure53 DOMPurify, published on 23 Jul 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

DOMPurify before 3.4.11 fails to clone the ALLOWED_ATTR allowlist when setConfig() is used with an uponSanitizeAttribute hook, allowing the hook to permanently mutate the shared allowlist. Attackers can register a hook that conditionally allows dangerous attributes like onerror for trusted elements, then submit untrusted content that inherits the polluted allowlist and executes event handlers as stored XSS.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-65898?

2 open source packages ship an affected version, including dompurify. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `dompurify` | npm | All versions | 3.4.11 |
| `dompurify` | npm | All versions | 3.4.11 |

Products: Cure53 Dompurify.

## How do I fix CVE-2026-65898?

Upgrade dompurify to 3.4.11 or later.

## Is CVE-2026-65898 being exploited?

There is no known exploitation of CVE-2026-65898 in the wild and no public exploit code.

## Other vulnerabilities in cure53 DOMPurify

- [CVE-2024-47875](https://insights.sbomify.com/CVE-2024-47875/): DOMPurify nesting-based mXSS (critical 10.0)
- [CVE-2024-48910](https://insights.sbomify.com/CVE-2024-48910/): DOMPurify vulnerable to tampering by prototype polution (critical 9.1)
- [CVE-2026-47423](https://insights.sbomify.com/CVE-2026-47423/): DOMPurify XSS via `selectedcontent` re-clone (high 8.2)
- [CVE-2024-45801](https://insights.sbomify.com/CVE-2024-45801/): Tampering by prototype polution in DOMPurify (high 7.3)
- [CVE-2026-49978](https://insights.sbomify.com/CVE-2026-49978/): DOMPurify IN_PLACE Sanitization Bypass via Attached Shadow Root Inside <template>.content (medium 6.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-65898 and fix it if it is affected.

What it is: CVE-2026-65898 is a medium-severity cross-site scripting vulnerability in cure53 DOMPurify, published on 23 Jul 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-65898 in the wild and no public exploit code.

Affected packages and fixed versions:
- dompurify (npm): affected all versions; fixed in 3.4.11
- dompurify (npm): affected all versions; fixed in 3.4.11

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-65898/ (Markdown: https://insights.sbomify.com/CVE-2026-65898/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-65898
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-65898
- OSV: https://osv.dev/vulnerability/CVE-2026-65898

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-65898/
Summaries are generated and may contain mistakes; the official description above is the record.