CVE-2021-4305 is a high-severity (CVSS 7.5) CWE-1333 vulnerability in robots-txt-guard. A fix is available for robots-txt-guard — see the affected versions and patch details below.
robots-txt-guard Inefficient Regular Expression Complexity vulnerability
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 CVE-2021-4305.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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.
robots-txt-guardnpmDescription
A vulnerability was found in Woorank robots-txt-guard. It has been rated as problematic. Affected by this issue is the function makePathPattern of the file lib/patterns.js. The manipulation of the argument pattern leads to inefficient regular expression complexity. The exploit has been disclosed to the public and may be used. The name of the patch is c03827cd2f9933619c23894ce7c98401ea824020. It is recommended to apply a patch to fix this issue. The identifier of this vulnerability is VDB-217448.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | robots-txt-guard | all versions | 1.0.2npm install robots-txt-guard@1.0.2 |
Affected Products
robots-txt-guardbridgelineDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for robots-txt-guard, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update robots-txt-guard to 1.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-4305 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.
Frequently Asked Questions
Is CVE-2021-4305 in your dependencies?
Find it across npm, including transitive dependencies.