CVE-2020-2503: Stored cross-site scripting vulnerability in QES

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-12-24 · updated 2026-06-17
Weakness: CWE-79

Description

If exploited, this stored cross-site scripting vulnerability could allow remote attackers to inject malicious code in File Station. QNAP has already fixed these issues in QES 2.1.1 Build 20201006 and later.

Affected products

QNAP Systems Inc. QES: before 2.1.1; 2.1.1, 2.1.1-build_20200211, 2.1.1-build_20200303, 2.1.1-build_20200319, 2.1.1-build_20200424, 2.1.1-build_20200515 (+1) — fixed in 2.1.1

How to fix

Upgrade to a fixed version: QNAP Systems Inc. QES 2.1.1. Check the vendor advisory for mitigations.

References

https://www.qnap.com/zh-tw/security-advisory/qsa-20-17
https://www.qnap.com/zh-tw/security-advisory/qsa-20-17

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