CVE-2026-118173

NONE
Published: 2026-10-27
Modified: 2026-10-28
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AI Threat Summary

CVE-2026-118173 is a moderate vulnerability affecting the target software. Threat hunters should monitor for exploit attempts and apply vendor patches immediately.

Description

MISP Guard, a proxy that enforces security policies on MISP feed data, contained an incomplete validation check for required taxonomy tags. When a feed event or its attributes carried tags belonging to a required taxonomy (for example, TLP), the guard only verified that at least one tag of that taxonomy matched the configured allowed list. It did not verify that every tag of the required taxonomy present on the event or attribute was in the allowed list. As a result, an event or attribute could simultaneously carry an allowed tag (e.g., tlp:clear) and a non-allowed tag (e.g., tlp:red or tlp:amber) and still pass the guard's policy check. This allowed data marked with a higher classification or sensitivity level to be distributed through feeds configured to only distribute lower-classification data, effectively bypassing the intended data-handling restrictions. The vulnerability affected both event-level and attribute-level tag validation, including attributes nested within objects and shadow attributes. An attacker with the ability to author or modify MISP events in a feed source could include non-allowed taxonomy tags alongside allowed ones to exfiltrate more sensitive data to feed consumers than the guard policy intended to permit.

Attack Chain
1
Reconnaissance

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

2
Initial Access

Attacker crafts malicious payload exploiting CVE-2026-118173 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-2026-118173
CVSS Score N/A
Published 2026-10-27
Exploited No
CISA KEV No
PoC Not public
References
External Resources
NVD Entry BleepingComputer The Hacker News