VDB
KO
MEDIUM 5.9

GHSA-jr45-8vmc-qm54

undici vulnerable to cross-user information disclosure via whitespace around equals in Cache-Control directives

Quick fix

GHSA-jr45-8vmc-qm54 — undici: upgrade to the fixed version with the command below.

npm install undici@7.29.0

Details

## Impact

Undici's cache interceptor mishandles optional whitespace (OWS) placed around the `=` of a qualified `no-cache` or `private` Cache-Control directive, such as `no-cache ="authorization"` (OWS before `=`) or `no-cache= "authorization"` (OWS after `=`). The parser either drops the directive entirely or stores a field name with literal quote characters, so the downstream cache decisions do not recognize the qualification and the response is stored.

In shared-cache mode, this allows a response containing one user's authenticated data to be served from cache to a subsequent caller, including an unauthenticated caller, when both requests resolve to the same cache key. The impact class is identical to CVE-2026-9678 (GHSA-pr7r-676h-xcf6); this advisory covers the whitespace-around-`=` bypass that the earlier fix did not normalize.

Affected applications are those that explicitly enable the cache interceptor (`interceptors.cache()`) in shared mode, forward `Authorization` headers upstream, and receive cacheable responses with qualified `private` or `no-cache` directives whose field-name list is padded with OWS around the `=`.

## Patches

Upgrade to undici v7.29.0 or v8.9.0.

## Workarounds

If upgrade is not immediately possible, disable shared-cache mode for traffic that includes `Authorization` headers, avoid caching responses to authenticated requests, or add `Vary: Authorization` upstream.

Are you affected?

Enter the version of the package you're using.

Affected packages

npm / undici
Introduced in: 7.0.0 Fixed in: 7.29.0
Fix npm install undici@7.29.0
npm / undici
Introduced in: 8.0.0 Fixed in: 8.9.0
Fix npm install undici@8.9.0

References