CVE-2026-2229 | ImpactThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range server_max_window_bits value (outside zlib's valid range of 8-15). When the server subsequently sends a compress
ImpactThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range server_max_window_bits value (outside zlib's valid range of 8-15). When the server subsequently sends a compressed frame, the client attempts to create a zlib InflateRaw instance with the invalid windowBits value, causing a synchronous RangeError exception that is not caught, resulting in immediate process termination.
The vulnerability exists because:
* The isValidClientWindowBits() function only validates that the value contains ASCII digits, not that it falls within the valid range 8-15
* The createInflateRaw() call is not wrapped in a try-catch block
* The resulting exception propagates up through the call stack and crashes the Node.js process
- 🔗 github.com/nodejs/undici/security/advisories/GHSA-v9…
- 🔗 hackerone.com/reports/3487486
- 🔗 cna.openjsf.org/security-advisories.html
- 🔗 datatracker.ietf.org/doc/html/rfc7692
- 🔗 nodejs.org/api/zlib.html
- 🔗 access.redhat.com/errata/RHSA-2026:13826
- 🔗 access.redhat.com/errata/RHSA-2026:17789
- 🔗 access.redhat.com/errata/RHSA-2026:21772
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📊 Historien-Charts — Criticals-Trend · Vendors · EPSS-Verteilung
| Tier | 2026-08-29 | 2026-09-17 |
|---|---|---|
| ≥90 % | 4 | 0 |
| ≥50 % | 4 | 0 |
| ≥10 % | 3 | 0 |
| <10 % | 304 | 300 |
CVE-2026-2229 | ImpactThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range server_max_window_bits value (outside zlib's valid range of 8-15). When the server subsequently sends a compress
ImpactThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatic