CVE-2021-21260
CWE-79Published: January 22, 2021· Updated: Jun 17, 2026
Official Description
Online Invoicing System (OIS) is open source software which is a lean invoicing system for small businesses, consultants and freelancers created using AppGini. In OIS version 4.0 there is a stored XSS which can enables an attacker takeover of the admin account through a payload that extracts a csrf token and sends a request to change password. It has been found that Item description is reflected without sanitization in app/items_view.php which enables the malicious scenario.
Technical Analysis
CVE-2021-21260 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.
From a weakness classification perspective (CWE-79): Cross-site scripting (XSS) vulnerabilities allow attackers to inject malicious scripts into web pages viewed by other users.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
Official Patches & Advisories
All References (4)
Quick Facts
Related CVEs (CWE-79)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-21260 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts