Bookstack
CVE-2020-26211
HIGH
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK
2 techniques across 2 tactics: Initial Access, Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS score of 8.7 (HIGH). Attack characteristics: network attack vector, low complexity, low privileges required, user interaction required. |
| Exploit ScenarioDerived | A remote attacker could inject malicious scripts into web pages viewed by other users by sending crafted requests to the affected application. |
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Alert meAnalysisAI
In BookStack before version 0.30.4, a user with permissions to edit a page could insert JavaScript code through the use of javascript: URIs within a link or form which would run, within the context. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. This Cross-Site Scripting (XSS) vulnerability could allow attackers to inject malicious scripts into web pages viewed by other users.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in composer
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. In BookStack before version 0.30.4, a user with permissions to edit a page could insert JavaScript code through the use of javascript: URIs within a link or form which would run, within the context of the current page, when clicked or submitted. Additionally, a user with permissions to edit a page could insert a particular meta tag which could be used to silently redirect users to a alternative location upon visit of a page. Dangerous content may remain in the database but will be removed before being displayed on a page. If you think this could have been exploited the linked advisory provides a SQL query to test. As a workaround without upgrading, page edit permissions could be limited to only those that are trusted until you can upgrade although this will not address existing exploitation of this vulnerability. The issue is fixed in BookStack version 0.30.4. Affected products include: Bookstackapp Bookstack. Version information: version 0.30.4.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
In BookStack before version 0.30.4, a user with permissions to edit a page could insert JavaScript code through the use of javascript: URIs within a link or form which would run, within the context of the current page, when clicked or submitted. Additionally, a user with permissions to edit a page could insert a particular meta tag which could be used to silently redirect users to a alternative location upon visit of a page. Dangerous content may remain in the database but will be removed before being displayed on a page. If you think this could have been exploited the linked advisory provides a SQL query to test. As a workaround without upgrading, page edit permissions could be limited to only those that are trusted until you can upgrade although this will not address existing exploitation of this vulnerability. The issue is fixed in BookStack version 0.30.4.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.
Affected Products (CPE)NVD
bookstack is vulnerable to Improper Access Control. Rated critical severity (CVSS 9.8), this vulnerability is remotely e
In BookStack before version 0.30.4, a user with permissions to edit a page could add an attached link which would execut
bookstack is vulnerable to Cross-Site Request Forgery (CSRF). Rated medium severity (CVSS 6.8), this vulnerability is re
Book Stack version 23.10.2 allows filtering local files on the server. Rated medium severity (CVSS 6.5), this vulnerabil
bookstack is vulnerable to Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'). Rated medium
bookstack is vulnerable to Unrestricted Upload of File with Dangerous Type. Rated medium severity (CVSS 6.5), this vulne
bookstack is vulnerable to Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'). Rated medium
bookstack is vulnerable to Server-Side Request Forgery (SSRF). Rated medium severity (CVSS 6.5), this vulnerability is r
bookstack is vulnerable to Unrestricted Upload of File with Dangerous Type. Rated medium severity (CVSS 5.7), this vulne
BookStack chapter export functionality allows unauthenticated remote attackers to bypass access controls via manipulatio
Cross-site Scripting (XSS) - Stored in GitHub repository bookstackapp/bookstack prior to v22.02.3. Rated medium severity
bookstack is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'). Rated m
Exploit-DB