SEPTEMBER 17, 2026
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Case File

CVE-2026-84890

MEDIUM · CVSS 5.9 EPSS 0.25% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-09-04 · Last synced 2026-09-17

CyberRota Analysis

AI-Generated

The vulnerability affects the undici library, specifically its decompress interceptor, which improperly handles untrusted Content-Encoding headers, allowing for the exploitation of memory resources. Attackers can leverage this flaw to send a small compressed payload that expands significantly in memory, potentially leading to excessive resource consumption and process crashes. Organizations using affected versions of undici should prioritize upgrading to versions 7.29.1 or 8.10.2 to mitigate this risk.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-84890
Severity
MEDIUM
CVSS
5.9
EPSS
0.25%

Original NVD 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.

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