CVE-2026-6733
undici vulnerable to HTTP response queue poisoning via keep-alive socket reuse
Summary
## Impact Undici's HTTP/1.1 client is vulnerable to response queue poisoning on reused keep-alive sockets. An attacker-controlled upstream server can inject an unsolicited HTTP/1.1 response onto an idle socket after a request completes. When the client dispatches the next request on that socket, it associates the injected response with the new request, causing responses to be delivered to the wrong requests. This requires an attacker-controlled or compromised upstream HTTP/1.1 server and keep-alive connection reuse. ## Patches Upgrade to undici v6.27.0, v7.28.0 or v8.5.0. ## Workarounds Disable keep-alive connection reuse by setting `keepAliveTimeout: 0` on the Client or Pool.
Affected packages
| Ecosystem | Package | Affected versions | Fixed versions |
|---|---|---|---|
| npm | undici | — | 6.27.0, 7.28.0, 8.5.0 |
Remediation: Upgrade to 6.27.0 or later.
References
Includes data from the GitHub Advisory Database, licensed under CC-BY 4.0.
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EPSS scores provided by the FIRST.org Exploit Prediction Scoring System.