CVE-2026-0707
📋 TL;DR
This vulnerability in Keycloak's Authorization header parser allows attackers to bypass authentication by using non-standard characters (like tabs) or case variations in Bearer tokens. It affects all Keycloak deployments that use Bearer token authentication. The flaw violates RFC 6750 specifications and could enable unauthorized access.
💻 Affected Systems
- Keycloak
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete authentication bypass allowing unauthorized access to protected resources and administrative functions.
Likely Case
Partial authentication bypass enabling access to some protected endpoints or user data.
If Mitigated
Minimal impact if proper token validation and additional authentication layers are implemented.
🎯 Exploit Status
Exploitation requires sending malformed Authorization headers but is technically simple once understood.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Red Hat advisory for specific fixed versions
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2026-0707
Restart Required: Yes
Instructions:
1. Check Red Hat advisory for fixed version. 2. Update Keycloak to patched version. 3. Restart Keycloak service. 4. Verify fix with proper token testing.
🔧 Temporary Workarounds
Implement custom token validation
allAdd middleware or filter to validate Authorization headers against RFC 6750 before Keycloak processes them.
Use reverse proxy validation
linuxConfigure reverse proxy (nginx, Apache) to reject non-compliant Authorization headers before reaching Keycloak.
nginx config: if ($http_authorization !~* "^Bearer\s+[A-Za-z0-9._~+/-]+=*$") { return 401; }
🧯 If You Can't Patch
- Implement network segmentation to restrict access to Keycloak instances
- Enable detailed logging of authentication attempts and monitor for unusual Authorization headers
🔍 How to Verify
Check if Vulnerable:
Test with malformed Authorization headers containing tabs or case variations in 'Bearer' scheme.Check Version:
Check Keycloak version in admin console or via: java -jar keycloak.jar --versionVerify Fix Applied:
Attempt same malformed headers after patch - should receive 401 Unauthorized responses.📡 Detection & Monitoring
Log Indicators:
- Authentication attempts with unusual Authorization headers
- 401 responses followed by successful 200s with similar requests
Network Indicators:
- HTTP requests with Authorization headers containing non-standard whitespace
- Case variations in 'Bearer' scheme
SIEM Query:
source="keycloak" AND (http.auth_header contains "\t" OR http.auth_header contains "bearer" OR http.auth_header contains "BEARER")