Spring gRPC auth ID retained on thread, pre-1.0.3
CVE-2026-40968 Published on April 28, 2026
Spring gRPC SecurityContext leaks across requests on authorization failure
When an authenticated user is denied access to a gRPC method, their authenticated identity remains bound to the gRPC worker thread and can be inherited by a subsequent unauthenticated request on the same thread. This may allow the subsequent user to gain escalated permissions.
Affected versions:
Spring gRPC: 1.0.0 - 1.0.2 (fixed in 1.0.3). Older, unsupported versions are also affected.
Vulnerability Analysis
CVE-2026-40968 is exploitable with network access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Weakness Type
What is a Separation of Privilege Vulnerability?
The product does not sufficiently compartmentalize functionality or processes that require different privilege levels, rights, or permissions. When a weakness occurs in functionality that is accessible by lower-privileged users, then without strong boundaries, an attack might extend the scope of the damage to higher-privileged users.
CVE-2026-40968 has been classified to as a Separation of Privilege vulnerability or weakness.
Products Associated with CVE-2026-40968
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Affected Versions
Spring gRPC:- Version 1.0.0 and below 1.0.3 is affected.