CVE-2026-40969 Spring CVE debrief

Who should care

Defenders responsible for Spring gRPC deployments, especially those using versions 1.0.0 to 1.0.2, should assess exposure and consider remediation by upgrading to version 1.0.3 or later. This includes reviewing authentication configurations, logging, and monitoring for potential information disclosure attempts. Security teams should prioritize verifying exposure and remediation based on deployment context.

Why it matters

CVE-2026-40969 is a vulnerability in Spring gRPC that allows information disclosure about authentication failures. Defenders should prioritize verifying exposure, especially for versions 1.0.0 to 1.0.2, and consider upgrading to version 1.0.3 or later. The vulnerability's impact is limited, but it may be useful for further attacks. Remediation priority is moderate, and evidence is limited to official CVE and NVD records.

• Potential information disclosure about authentication failures
• Possible use of disclosed information for further attacks
• Need to verify exposure in Spring gRPC deployments
• Prioritization of remediation based on deployment context

Technical summary

The raw message of every server-side AuthenticationException is returned to the unauthenticated remote caller in the gRPC status description, allowing an attacker to obtain information about the authentication failure. This vulnerability affects Spring gRPC versions 1.0.0 to 1.0.2 and is fixed in version 1.0.3. Defenders should prioritize verifying exposure in their Spring gRPC deployments and consider upgrading to the latest version. The vulnerability's technical impact is limited to information disclosure about authentication failures.

Defensive priority

Defenders should prioritize verifying exposure in their Spring gRPC deployments, especially for versions 1.0.0 to 1.0.2, and consider upgrading to version 1.0.3 or later.

Recommended defensive actions

• Verify Spring gRPC version and upgrade to 1.0.3 or later if necessary
• Review authentication configurations and logging for potential exposure
• Monitor for potential information disclosure attempts
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide information about the vulnerability, but details about potential exploitation or specific attacks are limited. Evidence is based on official CVE and NVD records, with limited additional information available. Defenders should verify exposure in their Spring gRPC deployments, especially for versions 1.0.0 to 1.0.2, and consider upgrading to version 1.0.3 or later.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.