undici up to 7.27.x/8.4.x Shared-Cache Mode interceptors.cache cache containing sensitive information

Summaryinfo

A vulnerability was found in undici up to 7.27.x/8.4.x and classified as problematic. The impacted element is the function interceptors.cache of the component Shared-Cache Mode. Executing a manipulation can lead to use of cache containing sensitive information. This vulnerability is tracked as CVE-2026-9678. The attack can be launched remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in undici up to 7.27.x/8.4.x and classified as problematic. This vulnerability affects the function interceptors.cache of the component Shared-Cache Mode. The manipulation with an unknown input leads to a use of cache containing sensitive information vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect confidentiality. CVE summarizes:

Impact: Undici's cache interceptor incorrectly classifies some responses as cacheable when the upstream Cache-Control header uses whitespace-padded qualified private or no-cache field names such as private=" authorization" or no-cache="\tauthorization". The parser preserves the surrounding whitespace, so later comparisons against the literal authorization field name fail 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. Affected applications are those that explicitly enable the cache interceptor (interceptors.cache()) in shared mode, forward Authorization headers upstream, and receive cacheable responses with non-canonical qualified private or no-cache directives. Patches: Upgrade to undici v7.28.0 or v8.5.0. 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.

The advisory is available at github.com. This vulnerability was named CVE-2026-9678 since 05/27/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1592 by the MITRE ATT&CK project.

Upgrading to version 7.28.0 or 8.5.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-37766). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Name

• undici

Version

• 7.0
• 7.1
• 7.2
• 7.3
• 7.4
• 7.5
• 7.6
• 7.7
• 7.8
• 7.9
• 7.10
• 7.11
• 7.12
• 7.13
• 7.14
• 7.15
• 7.16
• 7.17
• 7.18
• 7.19
• 7.20
• 7.21
• 7.22
• 7.23
• 7.24
• 7.25
• 7.26
• 7.27
• 8.0
• 8.1
• 8.2
• 8.3
• 8.4

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Discussion