What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-28 · updated 2026-10-26
• Weakness: CWE-209

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.

Affected products

• Spring gRPC: before 1.0.3 — fixed in 1.0.3
• Spring gRPC: from 1.0.0 before 1.0.3 — fixed in 1.0.3

How to fix

Upgrade to a fixed version: Spring gRPC 1.0.3; Spring gRPC 1.0.3. Check the vendor advisory for mitigations.

References

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

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