CORS Misconfiguration Enables Cross-Site Code Execution

open-webui before 0.3.14 contains a cross-origin resource sharing misconfiguration allowing arbitrary origins with allow_origins=* and authenticated requests to the /api/v1/functions endpoint. Attackers can execute arbitrary code on the openwebui instance by crafting malicious cross-site requests from attacker-controlled websites when an admin user visits them.

Casky was already ahead

This CVE exploits attack patterns that Casky's 283matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

Open-WebUI before version 0.3.14 suffers from a critical cross-origin resource sharing (CORS) misconfiguration that permits requests from any origin to access the /api/v1/functions endpoint. By setting allow_origins=* without proper validation, the application trusts all incoming requests, enabling attackers to craft malicious websites that execute arbitrary code when visited by authenticated administrators. This vulnerability is particularly dangerous because it combines two attack surfaces: weak CORS policies (CWE-613) with an unauthenticated code execution pathway. Organizations running vulnerable versions face immediate risk of full system compromise, credential theft, and lateral movement within their infrastructure, making patching to version 0.3.14 or later an urgent priority.

Casky's security skills detect the attack patterns underlying this vulnerability by mapping to MITRE ATT&CK techniques TA0004 (Privilege Escalation) and TA0006 (Credential Access). When Claude AI analyzes network traffic and application logs through Casky's 283 relevant skills, practitioners will identify suspicious cross-site requests originating from external domains hitting the /api/v1/functions endpoint with valid session tokens—the hallmark of CSRF-style exploitation. The platform's extended reasoning capabilities correlate CORS header anomalies (overly permissive Origin values) with subsequent API calls that deploy payloads to the functions endpoint, revealing the complete attack chain. Practitioners using Casky would see findings highlighting unauthorized function deployments tied to external domain origins, abnormal API call patterns from admin sessions, and evidence of code execution following cross-origin requests—enabling rapid detection and response before attackers establish persistence.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

283 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-56400.

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

Access with Stolen Session Cookie

identity access management · low

Run

MITRE ATT&CK Techniques

TA0004 TA0006

Investigate the attack patterns behind CVE-2026-56400

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