CVE-2021-21278 is a critical-severity (CVSS 9.8) CWE-74 vulnerability in rsshub. No vendor fix is recorded yet; mitigation options are listed below.
Risk of code injection
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
CVE-2021-21278 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 379,145 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
rsshubReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Some routes use eval or Function constructor, which may be injected by the target site with unsafe code, causing server-side security issues
Patches
Temporarily removed the problematic route and added a no-new-func rule to eslint
Self-built users should upgrade to 7f1c430 and later as soon as possible
Credits
Tencent Woodpecker Security Team
For more information
If you have any questions or comments about this advisory:
- Open an issue in https://github.com/DIYgod/RSSHub/issues
- Email us at [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | rsshub | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rsshub, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of rsshub has shipped for CVE-2021-21278 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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 CVE-2021-21278 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2021-21278. 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-2021-21278 in your dependencies?
O3 Security finds CVE-2021-21278 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.