CVE-2026-84890

Medium

Description

undici's decompress interceptor decompresses response bodies according to the untrusted Content-Encoding header. While the number of content-encoding layers is capped, the total decompressed output size is unbounded and there is no configuration option to limit it. A malicious or faulty upstream can therefore return a small compressed payload, a compression bomb, that expands to hundreds of megabytes or more in client memory, an asymmetric resource consumption that can exhaust memory and crash the process. This affects undici versions from 7.15.0 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.

SeverityMedium
CVSS5.9
Exploit probability—
ProductNodejs Undici
PublishedSep 4, 2026
First seenSep 4, 2026

How to fix

Update
  • nodejs undici7.29.1, 8.10.2 or later
  • undici7.29.1, 8.10.2 or later

Affected products

ProductAffected versionsFixed in
nodejs undici7.15.0 ≤ v < 7.29.1, 8.0.0 ≤ v < 8.10.27.29.1, 8.10.2
undicinpm7.15.0 ≤ v < 7.29.1, 8.0.0 ≤ v < 8.10.27.29.1, 8.10.2

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CVE-2026-84890 · Nodejs Undici · Dark Radar