Possible Citrix Bleed Session Token Leak via OpenID Configuration Endpoint (CVE-2023-4966) (via webserver)
- Category
- webserver
- Author
- HuntRule
- Published
- 2026-09-08
- Updated
- 2026-09-08
ATT&CK techniques
Initial Access → Cred AccessRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule detects requests to the NetScaler OpenID configuration discovery endpoint used to trigger CVE-2023-4966 memory disclosure. This maps to Citrix Bleed where an oversized Host header causes the appliance to leak adjacent memory containing session tokens. An attacker replays the leaked NSC_AAAC cookie to hijack authenticated sessions.
Reporting behind it
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
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