CVE-2019-25103
HIGHCVE-2019-25103 is a high-severity (CVSS 7.5) CWE-1333 vulnerability in simple-markdown. O3 Security confirms whether CVE-2019-25103 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Regular Expression Denial of Service in simple-markdown
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
simple-markdownnpmDescription
A vulnerability has been found in simple-markdown 0.5.1 and classified as problematic. Affected by this vulnerability is an unknown functionality of the file simple-markdown.js. The manipulation leads to inefficient regular expression complexity. The attack can be launched remotely. Upgrading to version 0.5.2 is able to address this issue. The patch is named 89797fef9abb4cab2fb76a335968266a92588816. It is recommended to upgrade the affected component. The associated identifier of this vulnerability is VDB-220639.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | simple-markdown | all versions | 0.5.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for simple-markdown. 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 simple-markdown to 0.5.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-25103 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-2019-25103 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-2019-25103. 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-2019-25103 in your dependencies?
O3 detects CVE-2019-25103 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.