GHSA-h857-2g56-468g is a high-severity (CVSS 7.6) Cross-site Scripting (XSS) vulnerability in @mattkrick/sanitize-svg. 1 public exploit reference exists, so weaponization risk is real. A fix is available for @mattkrick/sanitize-svg — see the affected versions and patch details below.
@mattkrick/sanitize-svg vulnerable to Cross-Site Scripting (XSS)
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-h857-2g56-468g.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-h857-2g56-468g plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@mattkrick/sanitize-svgnpmDescription
Impact
The sanitize-svg package uses a deny-list-pattern to sanitize SVGs to prevent cross-site scripting (XSS). In doing so, literal <script>-tags and on-event handlers were detected:
[...]
const svgEl = div.firstElementChild!
const attributes = Array.from(svgEl.attributes).map(({ name }) => name)
const hasScriptAttr = !!attributes.find((attr) => attr.startsWith('on'))
const scripts = svgEl.getElementsByTagName('script')
return scripts.length === 0 && !hasScriptAttr ? svg : null
[...]
There are more ways to embed JavaScript in XML files.
Anchor Tag (requires user to click link):
<svg viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg">
<a href="javascript:alert(document.domain)">
<text x="50" y="50" text-anchor="middle">Lauritz</text>
</a>
</svg>
Foreign Object Tag (no user interaction required):
<svg width="500" height="500" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<text x="20" y="35">Lauritz</text>
<foreignObject width="500" height="500">
<iframe xmlns="http://www.w3.org/1999/xhtml" src="javascript:confirm(document.domain);" width="400" height="250"/>
</foreignObject>
</svg>
As a result, downstream software that relies on sanitize-svg and expects resulting SVGs to be safe, may be vulnerable to XSS. We are aware of at least one downstream project for which this vulnerability had security implications.
Patches
This vulnerability was addressed in v0.4.0.
Workarounds
N/A
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @mattkrick/sanitize-svg | all versions | 0.4.0npm install @mattkrick/sanitize-svg@0.4.0 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @mattkrick/sanitize-svg, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @mattkrick/sanitize-svg to 0.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-h857-2g56-468g is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-h857-2g56-468g can be triaged on real exposure rather than presence alone.
Tailored to GHSA-h857-2g56-468g. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-h857-2g56-468g in your dependencies?
O3 Security finds GHSA-h857-2g56-468g across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.