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undici vulnerable to response truncation via oversized chunked responses in the dump interceptor

CVSS 3.1 3.7 LOWEUVD CVSS 3.1 3.7 CVSS 3.1 · ce714d77-add3-4f53-aff5-83d477b104bb · Secondary 3.7 LOWCVSS 3.1 · [email protected] · Primary 5.3 MEDIUMCVSS_V3 Publisher rating LOWFixed by undici 7.29.1Fixed by undici 8.10.2KEV status unknown

cve-program · CVE-2026-84947

Published

undici's dump interceptor reads and discards a response body up to a configurable maximum size. When a response declares a Content-Length that exceeds the maximum, the interceptor aborts cleanly, but when a response has no Content-Length and is chunked, the interceptor instead signals completion early once the accumulated size reaches the maximum, without pausing or aborting the request. Because the underlying parser keeps delivering body bytes, a second completion signal fires and trips an internal assertion, which aborts the request and tears down the connection. The application is left observing a misleading successful status with an empty or truncated body while the connection has actually been disconnected. This affects undici versions from 7.1.0 up to 7.29.1 and from 8.0.0 up to 8.10.2. Users should upgrade to undici 7.29.1 or 8.10.2.

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euvd · EUVD-2026-71517

Published

undici's dump interceptor reads and discards a response body up to a configurable maximum size. When a response declares a Content-Length that exceeds the maximum, the interceptor aborts cleanly, but when a response has no Content-Length and is chunked, the interceptor instead signals completion early once the accumulated size reaches the maximum, without pausing or aborting the request. Because the underlying parser keeps delivering body bytes, a second completion signal fires and trips an internal assertion, which aborts the request and tears down the connection. The application is left observing a misleading successful status with an empty or truncated body while the connection has actually been disconnected. This affects undici versions from 7.1.0 up to 7.29.1 and from 8.0.0 up to 8.10.2. Users should upgrade to undici 7.29.1 or 8.10.2.

Read the publisher's advisory

nvd · CVE-2026-84947

Published

undici's dump interceptor reads and discards a response body up to a configurable maximum size. When a response declares a Content-Length that exceeds the maximum, the interceptor aborts cleanly, but when a response has no Content-Length and is chunked, the interceptor instead signals completion early once the accumulated size reaches the maximum, without pausing or aborting the request. Because the underlying parser keeps delivering body bytes, a second completion signal fires and trips an internal assertion, which aborts the request and tears down the connection. The application is left observing a misleading successful status with an empty or truncated body while the connection has actually been disconnected. This affects undici versions from 7.1.0 up to 7.29.1 and from 8.0.0 up to 8.10.2. Users should upgrade to undici 7.29.1 or 8.10.2.

Read the publisher's advisory

osv · GHSA-2gqq-gqf2-x968

Published

### Impact undici's `interceptors.dump()` reads and discards response bodies up to a configurable `maxSize`. When a response declares a `Content-Length` that exceeds `maxSize`, the request is aborted cleanly. When a response is sent chunked (no `Content-Length`) and its body exceeds `maxSize`, it is not aborted: the interceptor ends the response early once the accumulated size reaches `maxSize`, and continued delivery from the parser triggers an internal assertion that is caught and turned into a request abort and connection tear-down. The application observes a misleading `200` with an empty or truncated body while the connection is disconnected. Any application using the dump interceptor against untrusted or misbehaving upstreams is affected. ### Patches Upgrade to `7.29.1` or `8.10.2`. The dump interceptor now enforces `maxSize` on both the declared and the received body size, aborting the request with a `RequestAbortedError` instead of returning a truncated response. ### Workarounds None. Avoid using `interceptors.dump()` with untrusted upstreams until upgraded.

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Sources read 12 Nov 16:29 UTC · 265 of 275 readable · 263 fully read · documentation 469/469 current