HomeCVE Intelligence › CVE-2026-34077
CVSS 7.5 HIGH Vulnerability

CVE-2026-34077: React Router vulnerable to Denial of Service via reflected user input in single-fetch

A DoS vulnerability exists in the React Router v7 [Framework Mode](https://reactrouter.com/start/modes#framework), as well as Remix v2.9.0+ with [Single Fetch](https://v2.remix.run/docs/guides/single-fetch) enabled. In…

7.5CVSS Score
HIGHSeverity
NOCISA KEV
VulnerabilityImpact Type

📋 Vulnerability Details

CVE IDCVE-2026-34077
Vendornpm
Affected Productreact-router
Vulnerability TypeVulnerability
CVSS Score7.5 (HIGH)
Actively Exploited❌ No known exploitation
Patch StatusSee Vendor Advisory →
Reported ByCYBERDUDEBIVASH SENTINEL APEX Intelligence (via github_advisories)

🔬 Technical Analysis

A DoS vulnerability exists in the React Router v7 [Framework Mode](https://reactrouter.com/start/modes#framework), as well as Remix v2.9.0+ with [Single Fetch](https://v2.remix.run/docs/guides/single-fetch) enabled. In some scenarios the underlying serialization algorithm can become a bottleneck when encoding specific types of data into server responses. Please upgrade to React Router v7.14.0 or later. > [!NOTE] > This does not impact your React Router application if you are using [Declarative Mode](https://reactrouter.com/start/modes#declarative) ( ) or [Data Mode](https://reactrouter.com/start/modes#data) (createBrowserRouter/ ).

🎯 Known Indicators of Compromise

{"type":"url","value":"https://reactrouter.com/start/modes#framework),","confidence_score":0.82,"first_seen":"2026-06-04","source_count":1} {"type":"url","value":"https://v2.remix.run/docs/guides/single-fetch)","confidence_score":0.82,"first_seen":"2026-06-04","source_count":1} {"type":"url","value":"https://reactrouter.com/start/modes#declarative)","confidence_score":0.82,"first_seen":"2026-06-04","source_count":1} {"type":"url","value":"https://reactrouter.com/start/modes#data)","confidence_score":0.82,"first_seen":"2026-06-04","source_count":1} {"type":"domain","value":"reactrouter.com","confidence_score":0.75,"first_seen":"2026-06-04","source_count":1}

📚 Advisory References

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