Listen to this Post
The CVE-2025-XXXX vulnerability in Backstage’s permission system allows unauthorized information leakage through conditional decisions returned by the permission policy. When a request is processed by the permission backend, conditional decisions (e.g., `CONDITIONAL` responses) may expose internal policy logic or metadata. Attackers exploiting this flaw can infer sensitive details about access control rules, even without direct policy access. The issue arises due to insufficient sanitization of decision responses before transmission.
If the permission system is unused or policies avoid conditional decisions, the impact is negligible. However, misconfigured policies may inadvertently disclose internal logic, aiding attackers in privilege escalation or policy bypass attempts. The flaw primarily affects Backstage instances with custom permission policies relying on conditional responses.
DailyCVE Form:
Platform: Backstage
Version: <0.6.0
Vulnerability: Policy info leak
Severity: Moderate
Date: 2025-04-16
What Undercode Say:
Exploitation:
1. Recon: Probe `/permissions/apply` endpoint with crafted requests.
- Leak Extraction: Analyze conditional responses for policy hints.
- Logic Inference: Map exposed conditions to bypass access controls.
Protection:
1. Patch: Upgrade to `[email protected]`.
2. Sanitization: Strip metadata from conditional decisions.
- Policy Review: Avoid sensitive data in condition responses.
Detection Commands:
curl -X POST http://backstage/permissions/apply -H "Content-Type: application/json" -d '{"resourceRef":"..."}'
Mitigation Script:
// Example: Sanitize conditional decisions
function sanitizeDecision(decision) {
if (decision.result === 'CONDITIONAL') {
delete decision.conditions.metadata;
}
return decision;
}
Log Analysis:
grep "CONDITIONAL" /var/log/backstage/permissions.log | jq '.conditions'
API Hardening:
backstage-config.yaml permissions: enforceSanitization: true
References:
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
