vanna-ai vanna FastAPI/Flask Server cross-domain policy

published 2026-04-02 7 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-18122

cvss: 4.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 5%
public exploits: 0; none known

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.

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 7 mo ago (2026-04-02)

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 5% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/August829/CVEP/issues/14 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	5.3	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
CNA	3.1	4.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N/E:P/RL:X/RC:R
CNA	3.0	4.3	CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N/E:P/RL:X/RC:R
CNA	2.0	4.0	AV:N/AC:L/Au:S/C:N/I:P/A:N/E:POC/RL:ND/RC:UR
CNA	4.0	2.1	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
CNA	3.1	4.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
CNA	2.0	4.0	AV:N/AC:L/Au:S/C:N/I:P/A:N

Affected products

vanna-ai vanna

Classification

Weakness

CWE-942 Permissive Cross-domain Security Policy with Untrusted Domains
CWE-346 Origin Validation Error

References

github.com /August829/CVEP/issues/14
exploit, issue-tracking
vuldb.com /vuln/354653
vdb-entry
vuldb.com /vuln/354653/cti
signature, permissions-required
vuldb.com /submit/780729
third-party-advisory

Sources

CVE List CVE-2026-5321
NVD CVE-2026-5321

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary