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HIGH

undici vulnerable to cross-origin cache poisoning via missing origin isolation in interceptors

Published Sep 4, 2026

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.

Affected products

Remediation

Red Hat statement

This flaw is present in the undici HTTP client library used by Node.js. When an application composes undici's Cache or Deduplicate interceptor directly onto a Client or Pool object (rather than onto an Agent), the library's internal cache and in-flight-request deduplication keys omit the destination origin. As a result, a cached or in-flight response captured for one upstream origin can be returned for a request intended for a different, trusted origin whenever the method, path, and relevant headers match. In the most severe demonstrated scenario, this allowed an attacker-controlled JWT to be accepted by the application as though it had been validated against a legitimate, trusted issuer, without that issuer ever being contacted — resulting in a full authentication bypass. Exploitation requires that the affected application attach the Cache or Deduplicate interceptor directly to a Client/Pool — the default Agent-based dispatch path is not affected, since Agent already carries the origin in its dispatch options — and that an attacker can influence or collide with the cache/deduplication key for at least one origin the application communicates with.).

Red Hat mitigation

Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible to undici 8.10.2 or later.

Weaknesses (1)

CWE-346

References (10)

Change history (0)

No recorded changes yet.

Sources

CVE.org / MITRE

Status PUBLISHED
Assigner openjs
Published Sep 4, 2026
Updated Sep 4, 2026
Reserved Sep 3, 2026
Link CVE-2026-85152

CISA Vulnrichment

Updated Sep 4, 2026

NVD

Status Analyzed
Modified Sep 16, 2026
Link CVE-2026-85152

Red Hat

Severity Important
Public date Sep 4, 2026
Bugzilla 2528717
Link CVE-2026-85152

ENISA EUVD

Assigner openjs
Published Sep 4, 2026
Updated Sep 4, 2026
Link EUVD-2026-71474

GitHub

Link GHSA-VP8M-P9JH-Q5PM