CVE-2022-31103
HIGHCVE-2022-31103 is a high-severity (CVSS 7.5) CWE-754 vulnerability in lettersanitizer. O3 Security confirms whether CVE-2022-31103 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Improper handling of CSS at-rules in lettersanitizer
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
lettersanitizernpmDescription
lettersanitizer is a DOM-based HTML email sanitizer for in-browser email rendering. All versions of lettersanitizer below 1.0.2 are affected by a denial of service issue when processing a CSS at-rule @keyframes. This package is depended on by react-letter, therefore everyone using react-letter is also at risk. The problem has been patched in version 1.0.2.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | lettersanitizer | all versions | 1.0.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for lettersanitizer. 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 lettersanitizer to 1.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-31103 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 CVE-2022-31103 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 CVE-2022-31103. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2022-31103 in your dependencies?
O3 detects CVE-2022-31103 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.