GHSA-5qr2-v392-m9g8 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in swc_html_minifier. O3 Security confirms whether GHSA-5qr2-v392-m9g8 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
SWC HTML minifier may allow script element breakout when minifying embedded JSON
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-5qr2-v392-m9g8.
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.
@swc/htmlnpmDescription
Impact
@swc/html minifies JSON contained in script elements such as
application/json and application/ld+json by parsing and serializing the
JSON value.
Before the patched versions, JSON serialization could convert escaped
less-than signs such as \u003C into literal < characters. If the JSON
contained an escaped </script> sequence, the generated HTML could terminate
the containing script element early because HTML tokenization occurs before
the JSON is consumed.
Applications that minify HTML containing attacker-controlled JSON data could therefore transform inert data into active markup. A crafted payload could execute script in the origin of the generated page.
Patches
The issue is fixed in:
@swc/html1.15.47swc_html_minifier59.0.0
The minifier now re-escapes less-than signs after JSON serialization, preserving the script element boundary.
Workarounds
Users who cannot upgrade can disable JSON minification with:
await minify(html, {
minifyJson: false,
});
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | swc_html_minifier | all versions | 59.0.0 |
| 📦npm | @swc/html | all versions | 1.15.47-nightly-20260729.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for swc_html_minifier. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update swc_html_minifier to 59.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-5qr2-v392-m9g8 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 pinpoints whether GHSA-5qr2-v392-m9g8 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-5qr2-v392-m9g8. 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-5qr2-v392-m9g8 in your dependencies?
O3 detects GHSA-5qr2-v392-m9g8 across crates.io, npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.