CVE-2026-73563 backstage CVE debrief

Who should care

Defenders and administrators of Backstage deployments with dynamic client registration and client ID metadata document features enabled should assess exposure and prioritize verification.

Why it matters

CVE-2026-73563 allows attackers to obtain OAuth authorization codes in Backstage deployments with specific configurations. Defenders should assess exposure, verify configurations, and update to version 0.29.2 or later if affected.

• Potential unauthorized access to OAuth authorization codes
• Need for verification of affected deployments and configurations
• Possible impact on confidentiality due to code exposure

Technical summary

The vulnerability in Backstage's experimental features allows an attacker to obtain an OAuth authorization code by exploiting improper glob matching of allowedRedirectUriPatterns and allowedClientIdPatterns. This affects deployments with custom wildcard-hostname or protocol-less patterns configured. Defenders should assess exposure and prioritize verification of affected deployments, especially those with custom wildcard-hostname or protocol-less patterns configured. The issue arises from the use of full-string matcher.isMatch glob matching for auth.experimentalDynamicClientRegistration.allowedRedirectUriPatterns and the auth.experimentalClientIdMetadataDocuments allowedClientIdPatterns and allowedRedirectUriP

Defensive priority

Defenders should assess exposure and prioritize verification of affected deployments, especially those with custom wildcard-hostname or protocol-less patterns configured.

Recommended defensive actions

• Assess exposure of Backstage deployments with dynamic client registration and client ID metadata document features enabled
• Verify configurations of allowedRedirectUriPatterns and allowedClientIdPatterns
• Update to version 0.29.2 or later if affected
• 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 details on the vulnerability, its impact, and affected configurations. However, specific details on exploitation and remediation are limited. Defenders should verify configurations of allowedRedirectUriPatterns and allowedClientIdPatterns, assess exposure, and update to version 0.29.2 or later if affected. Evidence from the CVE Program and NVD suggests that the vulnerability affects deployments with custom wildcard-hostname or protocol-less patterns configured.

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.