CVE-2026-85152
Received Received - Intake

Origin Cache Poisoning in Undici 8.10.0

Publication date: 2026-09-04

Last updated on: 2026-09-04

Assigner: openjs

Description
undici 8.10.0 omits the destination origin from the cache and request-deduplication keys when the cache or deduplicate interceptor is composed directly onto a Client or Pool. Because the internal cache key falls back to an empty origin string, a cacheable or in-flight response from one upstream origin is returned for a request to a different, trusted origin whenever the method, path, and relevant headers match, which permits cross-origin information disclosure and persistent cache poisoning. The reporter demonstrated a full authentication bypass in which a JWT signed with an attacker-controlled key was accepted as belonging to a trusted issuer, and the trusted origin was never contacted. This is a regression introduced in 8.10.0 and affects undici versions from 8.10.0 up to 8.10.2. Applications using an Agent, which carries the origin in its dispatch options, are not affected. Users should upgrade to undici 8.10.2.

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Meta Information

Published
2026-09-04
Last Modified
2026-09-04
Generated
2026-09-05
AI Q&A
2026-09-04
EPSS Evaluated
N/A
NVD
CVE-2026-85152
EUVD
EUVD-2026-71474

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
undici undici to 8.10.2 (inc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-346 The product does not properly verify that the source of data or communication is valid.

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Executive Summary

This vulnerability in undici 8.10.0 affects cache and request deduplication when interceptors are directly composed onto a Client or Pool. It causes the destination origin to be omitted from cache and deduplication keys, leading to responses from one origin being incorrectly returned for requests to a different origin if the method, path, and headers match. This enables cross-origin data leaks and cache poisoning.

Detection Guidance

This vulnerability affects undici versions 8.10.0 to 8.10.2. To detect it, check the installed version of undici in your project using commands like 'npm list undici' or 'yarn list undici'. If the version is within the affected range, the system is vulnerable.

Impact Analysis

An attacker could exploit this to intercept sensitive data sent to a trusted origin or poison the cache with malicious responses. For example, a JWT signed by an attacker could be accepted as valid for a trusted issuer without contacting the trusted origin, leading to authentication bypass and unauthorized access.

Compliance Impact

This vulnerability could lead to unauthorized data exposure or manipulation, violating confidentiality and integrity requirements in GDPR and HIPAA. Organizations using affected undici versions may face compliance violations due to potential data breaches or unauthorized access.

Mitigation Strategies

Upgrade undici to version 8.10.2 or later immediately. If using npm, run 'npm update undici'. If using yarn, run 'yarn upgrade undici'. Ensure no applications are using versions 8.10.0 to 8.10.2.

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