CVE-2022-31100
MEDIUMCVE-2022-31100 is a medium-severity (CVSS 6.5) Reachable Assertion vulnerability in rulex. O3 Security confirms whether CVE-2022-31100 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Reachable Assertion in rulex
Blast Radius
rulexReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
rulex is a new, portable, regular expression language. When parsing untrusted rulex expressions, rulex may crash, possibly enabling a Denial of Service attack. This happens when the expression contains a multi-byte UTF-8 code point in a string literal or after a backslash, because rulex tries to slice into the code point and panics as a result. This is a security concern for you, if your service parses untrusted rulex expressions (expressions provided by an untrusted user), and your service becomes unavailable when the thread running rulex panics. The crashes are fixed in version 0.4.3. Affected users are advised to update to this version. The only known workaround for this issue is to assume that regular expression parsing will panic and to add logic to catch panics.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | rulex | all versions | 0.4.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rulex. 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 rulex to 0.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-31100 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-2022-31100 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-2022-31100. 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-2022-31100 in your dependencies?
O3 detects CVE-2022-31100 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.