CVE-2026-30587
Description
A flaw was found in Seafile Server and its Seadoc editor. This Stored Cross-Site Scripting (XSS) vulnerability allows authenticated remote attackers to inject malicious JavaScript code. The application fails to properly sanitize WebSocket messages during document structure updates. By exploiting this, an attacker can execute arbitrary client-side scripts, potentially leading to information disclosure or unauthorized actions within a user's browser.
Statement
This MODERATE stored XSS vulnerability in Seafile Server's Seadoc editor allows authenticated users to inject malicious scripts via unsanitized WebSocket messages. Exploitation requires low privileges (any authenticated user) and user interaction (victim views document). Impact is high to confidentiality and integrity. Affects Seafile Server 13.0.15, 13.0.16-pro, 12.0.14 and prior. Fixed in 13.0.17, 13.0.17-pro, and 12.0.20-pro.
Understanding the Weakness (CWE)
Access Control,Confidentiality
Technical Impact: Bypass Protection Mechanism; Read Application Data
The most common attack performed with cross-site scripting involves the disclosure of private information stored in user cookies, such as session information. Typically, a malicious user will craft a client-side script, which -- when parsed by a web browser -- performs some activity on behalf of the victim to an attacker-controlled system (such as sending all site cookies to a given E-mail address). This could be especially dangerous to the site if the victim has administrator privileges to manage that site. This script will be loaded and run by each user visiting the web site. Since the site requesting to run the script has access to the cookies in question, the malicious script does also.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
In some circumstances it may be possible to run arbitrary code on a victim's computer when cross-site scripting is combined with other flaws, for example, "drive-by hacking."
Confidentiality,Integrity,Availability,Access Control
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism; Read Application Data
The consequence of an XSS attack is the same regardless of whether it is stored or reflected. The difference is in how the payload arrives at the server. XSS can cause a variety of problems for the end user that range in severity from an annoyance to complete account compromise. Some cross-site scripting vulnerabilities can be exploited to manipulate or steal cookies, create requests that can be mistaken for those of a valid user, compromise confidential information, or execute malicious code on the end user systems for a variety of nefarious purposes. Other damaging attacks include the disclosure of end user files, installation of Trojan horse programs, redirecting the user to some other page or site, running "Active X" controls (under Microsoft Internet Explorer) from sites that a user perceives as trustworthy, and modifying presentation of content.
Frequently Asked Questions
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