undici vulnerable to cross-user information disclosure via whitespace around equals in Cache-Control directives
## 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.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-14643US | high7.5 | — | ||
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 befor… | ||||
references
External citations — patches, advisories, analysis.
- https://cna.openjsf.org/security-advisories.htmlWEB
- https://github.com/nodejs/undiciPACKAGE
- https://github.com/nodejs/undici/commit/85a240551c9feb8b8a0ecc56c84b2b3015add8a9WEB
- https://github.com/nodejs/undici/commit/cb105d7c79069150982fa11acada0dd94a60dbbcWEB
- https://github.com/nodejs/undici/releases/tag/v7.29.0WEB
- https://github.com/nodejs/undici/releases/tag/v8.9.0WEB
- https://github.com/nodejs/undici/security/advisories/GHSA-jr45-8vmc-qm54WEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-14643ADVISORY
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