CVE-2026-5321Public exploitNetwork attack vector

Cross-origin data modification via credentialed origin reflection

Published Apr 2, 2026 · Updated Apr 2, 2026

Cross-origin policy error in Vanna 2.0.0 through 2.0.2 allows remote authenticated users to modify data via credentialed cross-origin requests. The FastAPI and Flask server CORS policy reflects an arbitrary Origin value while permitting credentials instead of checking a trusted-origin allowlist. Valid low-privilege credentials are required, and successful requests can modify server-side data available to that account.

CVSS severity4.3
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Cross-origin policy error in Vanna 2.0.0 through 2.0.2 allows remote authenticated users to modify data via credentialed cross-origin requests. The FastAPI and Flask server CORS policy reflects an arbitrary Origin value while permitting credentials instead of checking a trusted-origin allowlist. Valid low-privilege credentials are required, and successful requests can modify server-side data available to that account.

The record

CVE
CVE-2026-5321
Published
Apr 2, 2026
Updated
Apr 2, 2026
Vendor
Vanna AI
Product
Vanna
Classifications
CWE-346, CWE-942, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 2, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.0.0
  2. Affected versionversion=2.0.1
  3. Affected versionversion=2.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Vanna AI · Vannaversion=2.0.0; version=2.0.1; version=2.0.2

Published CVSS scores

4.3VulDBCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
4.3VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
2.1VulDBCVSS: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
4.0VulDBAV:N/AC:L/Au:S/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-346Origin Validation Error
CWE-942Permissive Cross-domain Security Policy with Untrusted Domains
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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