CVE-2026-84933
Received
Received - Intake
Cache Poisoning in Undici HTTP Client
Vulnerability report for CVE-2026-84933, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-09-04
Last updated on: 2026-09-04
Assigner: openjs
Description
Description
undici's cache interceptor does not handle the Set-Cookie response header anywhere in its cache path, so it neither refuses to store nor strips that header. In shared cache mode, which is the default, an otherwise cacheable response that carries a Set-Cookie header, for example one marked with a public and max-age directive, is stored and then re-served to a later caller that matches the same cache key. As a result one caller's cookie is disclosed to a different caller, and an untrusted server can inject cookies into cached responses served to all subsequent callers. This violates the requirement that a shared cache must not store cookies. This affects undici versions from 7.0.0 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 Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| undici | undici | From 7.0.0 (inc) to 7.29.1 (inc) |
| undici | undici | From 8.0.0 (inc) to 8.10.2 (inc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-524 | The code uses a cache that contains sensitive information, but the cache can be read by an actor outside of the intended control sphere. |
| CWE-200 | The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. |
