# CVE-2026-61784: xhtml-purifier has HTML attribute-injection (sanitizer bypass) that leads to XSS

> Attackers can inject JavaScript via unencoded attribute values in xhtml-purifier, bypassing sanitization to execute scripts in victim browsers.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 24 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-j8r4-32c5-33rc

## What is CVE-2026-61784?

CVE-2026-61784 is a medium-severity cross-site scripting vulnerability in cstigler node-xhtml-purifier, published on 24 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

xhtml-purifier is a Node.js library to take in raw/unknown/untrusted HTML and output cleaned, purified, trusted HTML. Versions prior to 0.4.3 do not HTML-entity-encode attribute values when serializing its sanitized output. In attributeString() (XHTMLPurifier.js, around line 148) the attribute value is concatenated directly into a double-quoted attribute without encoding. As a result, an attacker-controlled value in any allowed attribute (class, style, title, alt, src, href) can include a double-quote character to break out of the attribute and inject an additional attribute, such as a JavaScript event handler (for example onmouseover or onerror). The injected handler survives sanitization and executes when the output is rendered, which is a sanitizer bypass leading to cross-site scripting. The fix in version 0.4.3 HTML-entity-encodes attribute values before serialization.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation), CWE-116 (Improper Encoding or Escaping of Output)

## Which versions are affected by CVE-2026-61784?

2 open source packages ship an affected version, including xhtml-purifier.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `xhtml-purifier` | npm | All versions | 0.4.3 |
| `xhtml-purifier` | npm | All versions | 0.4.3 |

## How do I fix CVE-2026-61784?

Upgrade xhtml-purifier to 0.4.3 or later.

## Is CVE-2026-61784 being exploited?

There is no known exploitation of CVE-2026-61784 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-61784 and fix it if it is affected.

What it is: CVE-2026-61784 is a medium-severity cross-site scripting vulnerability in cstigler node-xhtml-purifier, published on 24 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-61784 in the wild and no public exploit code.

Affected packages and fixed versions:
- xhtml-purifier (npm): affected all versions; fixed in 0.4.3
- xhtml-purifier (npm): affected all versions; fixed in 0.4.3

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-2026-61784/ (Markdown: https://insights.sbomify.com/CVE-2026-61784/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-61784
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-61784
- OSV: https://osv.dev/vulnerability/CVE-2026-61784

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-61784/
Summaries are generated and may contain mistakes; the official description above is the record.