Medium severity · published Sep 4, 2026
CVE-2026-84947
undici vulnerable to response truncation via oversized chunked responses in the dump interceptor
5.3
CVSS
0.2%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 9% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
UN
undici · undici
7.1.0 before 7.29.1; 8.0.0 before 8.10.2 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-84947
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-84947
Third Party Advisory
https://cna.openjsf.org/security-advisories.html
Vendor Advisory
https://github.com/nodejs/undici/security/advisories/GHSA-2gqq-gqf2-x968
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