Is CVE-2026-84947 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-84947 being exploited in the wild.

How severe is CVE-2026-84947?

Low severity, with a CVSS score of 3.7, published 4 September 2026.

Which products and versions are affected?

undici (npm) SEMVER:introduced=7.1.0,fixed=7.29.1.

Is there a fix for CVE-2026-84947?

Yes. undici (npm): upgrade to 7.29.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-84947 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-84947?

Check whether you run undici (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-84947: undici response truncation via oversized chunked responses in dump interceptor

CVE-2026-84947 · Severity: low · CVSS 3.7 · Published 2026-09-04

undici is a popular Node.js HTTP client library used by many applications to fetch data from remote servers. The dump interceptor—a tool for capturing and discarding response bodies up to a specified size limit—fails to properly handle responses sent without a declared size when they exceed the limit. This causes the application to report a successful response with truncated or empty data while silently disconnecting from the server, potentially causing data loss and connection reliability issues.

Technologies: undici (npm). Vendors: npm.

Quick answers

Is CVE-2026-84947 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-84947 being exploited in the wild.
How severe is CVE-2026-84947?: Low severity, with a CVSS score of 3.7, published 4 September 2026.
Which products and versions are affected?: undici (npm) SEMVER:introduced=7.1.0,fixed=7.29.1.
Is there a fix for CVE-2026-84947?: Yes. undici (npm): upgrade to 7.29.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-84947 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-84947?: Check whether you run undici (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

undici (npm): upgrade to 7.29.1 or later
```
npm install undici@7.29.1
```

Technical details

The vulnerability is an input validation and improper exception handling issue (CWE-20, CWE-248) in undici's dump interceptor. When a chunked response (no Content-Length header) exceeds maxSize, the interceptor signals early completion but the underlying HTTP parser continues delivering body bytes, triggering a second completion signal that violates an internal assertion. This causes the connection to be torn down and the application to observe a misleading 200 status code with truncated content. The attack requires network reachability to a misbehaving or untrusted upstream server; no authentication or user interaction is required. Affected versions are 7.1.0–7.29.0 and 8.0.0–8.10.1; patches are available in 7.29.1 and 8.10.2.

Affected products

OpenJS Foundation undici 7.1.0 to 7.29.0, 8.0.0 to 8.10.1

Identifiers

CVE-2026-84947
GHSA-2gqq-gqf2-x968

Timeline

2026-09-04: disclosed: CVE-2026-84947 and GHSA-2gqq-gqf2-x968 published
2026-09-04: patched: Patches released in undici 7.29.1 and 8.10.2

References

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