CVE-2026-9678

A flaw was found in Undici. The cache interceptor in shared-cache mode incorrectly classifies certain responses as cacheable due to improper handling of whitespace-padded Cache-Control header field names. This vulnerability allows an unauthenticated attacker to access authenticated user data from the cache, leading to information disclosure. This occurs when both authenticated and unauthenticated requests resolve to the same cache key.

This Moderate information disclosure flaw in Undici's cache interceptor, when configured in shared-cache mode, allows an unauthenticated attacker to retrieve sensitive authenticated user data. This is due to incorrect parsing of Cache-Control headers containing whitespace-padded field names, leading to cached responses being served improperly. Red Hat products are affected if they explicitly enable shared-cache mode, forward Authorization headers, and process non-canonical Cache-Control directives.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.