CVE-2026-14643: undici vulnerable to cross-user information disclosure via whitespace around equals in Cache-Control directives

Vulnerability summary

CVE-2026-14643 is a high (CVSS 7.5) Interpretation Conflict vulnerability in nodejs undici. EPSS estimates a 0.40% chance of exploitation in the next 30 days, higher than 33.8% of scored vulnerabilities.

Timeline

1. 29-07-2026
   PublishedVulnerability first disclosed.
2. 30-07-2026
   Last modifiedVulnerability information updated.

Description

undici's cache interceptor mishandles optional whitespace placed around the equals sign of a qualified no-cache or private Cache-Control directive. In undici from 7.0.0 up to before 7.29.0 and from 8.0.0 up to before 8.9.0, the parser either drops the directive or stores a field name with literal quote characters, so the cache decision fails to recognize the qualification and the response is stored. In shared-cache mode, this lets a response containing one user's authenticated data be served from cache to a later caller, including an unauthenticated one, when both requests resolve to the same cache key. It affects applications that enable the cache interceptor in shared mode, forward Authorization headers upstream, and receive cacheable responses with qualified directives padded with whitespace around the equals sign. This is the whitespace-around-equals variant that the fix for CVE-2026-9678 did not normalize, and it is fixed in undici 7.29.0 and 8.9.0.

• CWE-436Interpretation ConflictProduct A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state.
• CWE-524Use of Cache Containing Sensitive InformationThe code uses a cache that contains sensitive information, but the cache can be read by an actor outside of the intended control sphere.