Vulnerability Description
The undici WebSocket client is vulnerable to a denial-of-service attack via unbounded memory consumption during permessage-deflate decompression. When a WebSocket connection negotiates the permessage-deflate extension, the client decompresses incoming compressed frames without enforcing any limit on the decompressed data size. A malicious WebSocket server can send a small compressed frame (a "decompression bomb") that expands to an extremely large size in memory, causing the Node.js process to exhaust available memory and crash or become unresponsive. The vulnerability exists in the PerMessageDeflate.decompress() method, which accumulates all decompressed chunks in memory and concatenates them into a single Buffer without checking whether the total size exceeds a safe threshold.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Nodejs | Undici | < 6.24.0 |
Related Weaknesses (CWE)
References
- https://cna.openjsf.org/security-advisories.htmlVendor Advisory
- https://datatracker.ietf.org/doc/html/rfc7692Technical Description
- https://github.com/nodejs/undici/security/advisories/GHSA-vrm6-8vpv-qv8qVendor Advisory
- https://hackerone.com/reports/3481206Permissions Required
FAQ
What is CVE-2026-1526?
CVE-2026-1526 is a vulnerability with a CVSS score of 7.5 (HIGH). The undici WebSocket client is vulnerable to a denial-of-service attack via unbounded memory consumption during permessage-deflate decompression. When a WebSocket connection negotiates the permessage-...
How severe is CVE-2026-1526?
CVE-2026-1526 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-1526?
Check the references section above for vendor advisories and patch information. Affected products include: Nodejs Undici.