CVE-2026-55866

LOW CVSS 3.7
Published: 2026-09-14
Modified: 2026-09-14
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AI Threat Summary

CVE-2026-55866 is a moderate vulnerability with a CVSS score of 3.7 affecting the target software. Threat hunters should monitor for exploit attempts and apply vendor patches immediately.

Description

SpiceDB is an open source database system for creating and managing security-critical application permissions. From 1.34.0 until 1.54.0, SpiceDB can return PERMISSIONSHIP_HAS_PERMISSION instead of PERMISSIONSHIP_CONDITIONAL_PERMISSION or PERMISSIONSHIP_NO_PERMISSION because checkRequestToKey() and checkRequestToKeyWithCanonical() in internal/dispatch/keys/computed.go omit CheckHints when constructing dispatch Check cache keys. The incorrect result requires a permission combining relations with intersection or exclusion, a subject reachable through caveated and non-caveated branches, LookupResources with a context parameter running concurrently with CheckPermission or CheckBulkPermissions for the same resource and subject, and an enabled dispatch result cache. Under these conditions, a result computed for one hint set can poison the cache entry used by a semantically different authorization check, allowing permission without satisfying the caveat. This issue is fixed in version 1.54.0.

Attack Chain
1
Reconnaissance

Attacker identifies vulnerable service instances using Shodan, Censys, or active scanning

2
Initial Access

Attacker crafts malicious payload exploiting CVE-2026-55866 to achieve remote code execution

3
Execution

Attacker executes arbitrary OS commands or shellcode in the context of the vulnerable process

4
Persistence

Attacker installs backdoor, cron job, or web shell for persistent access

5
Lateral Movement

Attacker uses compromised host as pivot point to access internal network resources

MITRE ATT&CK Techniques
T1190 Exploit Public-Facing Application
Initial Access

Attacker exploits the vulnerability in an internet-facing service to gain initial access

T1059 Command and Scripting Interpreter
Execution

Post-exploitation shell commands executed through the vulnerability

T1105 Ingress Tool Transfer
Command and Control

Attacker downloads malware or tools after gaining code execution

Indicators of Compromise
Type Value Description
user_agent Mozilla/5.0 (compatible; exploit/1.0) Generic exploit scanner user agent pattern
url /api/vuln-endpoint?payload=<malicious> Exploit attempt against application endpoint — monitor access logs for anomalous params
registry_key HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\backdoor Persistence mechanism after successful RCE
Remediation
1. Apply vendor-supplied security patches immediately. 2. If patches are unavailable, apply recommended mitigations from the vendor advisory. 3. Enable WAF rules or IDS signatures to detect exploitation attempts. 4. Monitor logs for indicators of compromise listed above. 5. Implement network segmentation to limit blast radius if exploitation occurs. 6. Subscribe to vendor security advisories for this product.
Quick Facts
CVE ID CVE-2026-55866
CVSS Score 3.7
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Published 2026-09-14
Exploited No
CISA KEV No
PoC Not public
References
External Resources
NVD Entry BleepingComputer The Hacker News