GHSA-j533-2g8v-pmpg is a high-severity (CVSS 7.5) CWE-1333 vulnerability in simple-markdown. 1 public exploit reference exists, so weaponization risk is real. A fix is available for simple-markdown — see the affected versions and patch details below.
Regular Expression Denial of Service in simple-markdown
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-j533-2g8v-pmpg 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 377,166 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.
simple-markdownnpmDescription
A vulnerability, which was classified as problematic, was found in simple-markdown 0.6.0. Affected is an unknown function of the file simple-markdown.js. The manipulation with the input <<<<<<<<<<:/:/:/:/:/:/:/:/:/:/ leads to inefficient regular expression complexity. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. Upgrading to version 0.6.1 is able to address this issue. The name of the patch is 015a719bf5cdc561feea05500ecb3274ef609cd2. It is recommended to upgrade the affected component. VDB-220638 is the identifier assigned to this vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | simple-markdown | all versions | 0.6.1npm install simple-markdown@0.6.1 |
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 simple-markdown, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update simple-markdown to 0.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-j533-2g8v-pmpg 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-j533-2g8v-pmpg can be triaged on real exposure rather than presence alone.
Tailored to GHSA-j533-2g8v-pmpg. 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-j533-2g8v-pmpg in your dependencies?
O3 Security finds GHSA-j533-2g8v-pmpg across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.