Is there a public PoC exploit available for CVE-2026-5321?

Yes, a public proof-of-concept exploit is available for CVE-2026-5321. Prioritise patching immediately. EPSS: 0.0%.

Cors Misconfiguration CVE-2026-5321

Q: What is the CVSS score of CVE-2026-5321?

CVE-2026-5321 has a CVSS 4.0 base score of 2.1 (Low). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.0%.

EUVD-2026-18122 LOW

Permissive Cross-domain Security Policy with Untrusted Domains (CWE-942)

2026-04-02 VulDB

GHSA-fp27-q2f5-phx3

Cors Misconfiguration Information Disclosure Python

2.1

CVSS 4.0 · NVD

Severity by source

NVD PRIMARY

2.1 LOW

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

Severity Changed

Apr 29, 2026 - 01:11 NVD

MEDIUM LOW

CVSS changed

Apr 29, 2026 - 01:11 NVD

5.3 (MEDIUM) 2.1 (LOW)

PoC Detected

Apr 03, 2026 - 16:10 vuln.today

Public exploit code

EUVD ID Assigned

Apr 02, 2026 - 05:15 euvd

EUVD-2026-18122

Analysis Generated

Apr 02, 2026 - 05:15 vuln.today

CVE Published

Apr 02, 2026 - 04:45 nvd

MEDIUM 5.3

DescriptionCVE.org

A flaw has been found in vanna-ai vanna up to 2.0.2. Affected by this issue is some unknown functionality of the component FastAPI/Flask Server. Executing a manipulation can lead to permissive cross-domain policy with untrusted domains. The attack can be launched remotely. The exploit has been published and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

AnalysisAI

Cross-Origin Resource Sharing (CORS) misconfiguration in vanna-ai vanna up to version 2.0.2 allows authenticated remote attackers to establish permissive cross-domain policies with untrusted domains, leading to information disclosure. The vulnerability affects the FastAPI/Flask Server component and has publicly available exploit code; however, the vendor has not responded to early disclosure attempts. With a CVSS score of 5.3 and confirmed public exploit availability, this represents a moderate-risk authentication-gated information exposure issue.

Technical ContextAI

The vulnerability stems from improper CORS (Cross-Origin Resource Sharing) policy configuration in vanna-ai's FastAPI or Flask web server component (CWE-942: Permissive Cross-domain Policy with Untrusted Domains). CORS misconfiguration allows a web application to accept requests from unauthorized or insufficiently validated origins, enabling cross-site request forgery (CSRF) and data exfiltration attacks. The affected product is vanna-ai vanna (CPE: cpe:2.3:a:vanna-ai:vanna:*:*:*:*:*:*:*:*), a Python-based framework. The flaw permits manipulation of the server's domain validation logic, allowing an attacker to bypass origin restrictions and access sensitive data across domain boundaries when authenticated to the application.

RemediationAI

Upgrade vanna-ai vanna to a version after 2.0.2 once the vendor releases a patched build addressing the CORS misconfiguration. At time of analysis, no vendor-released patch version has been independently confirmed, likely due to the vendor's non-responsiveness to early disclosure. As an interim workaround, operators should: (1) implement network-level origin filtering or a Web Application Firewall (WAF) rule restricting CORS requests to trusted domains only, (2) enforce strict CORS policies in the application configuration if user-configurable settings exist, and (3) monitor for suspicious cross-origin requests in access logs. Consult the VulDB advisory at https://vuldb.com/vuln/354653 for updates when patches become available. For detailed remediation guidance, check the vendor's security advisory channels, though vendor responsiveness has been limited.