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Cross-Site Scripting in BookStack

Moderate severity GitHub Reviewed Published May 2, 2020 in BookStackApp/BookStack • Updated Jan 9, 2023

Package

composer ssddanbrown/bookstack (Composer)

Affected versions

>= 0.18.0, < 0.29.2

Patched versions

0.29.2

Description

Impact

A user with permission to create comments could POST HTML directly to the system to be saved in a comment, which would then be executed/displayed to others users viewing the comment. Through this vulnerability custom JavaScript code could be injected and therefore ran on other user machines.

This most impacts scenarios where not-trusted users are given permission to create comments.

Patches

The issue was addressed in BookStack v0.29.2.

After upgrading, The command php artisan bookstack:regenerate-comment-content should be ran to remove any pre-existing dangerous content.

Workarounds

Comments can be disabled in the system settings to prevent them being shown to users. Alternatively, comment creation permissions can be altered as required to only those who are trusted but this will not address existing exploitation of this vulnerability.

References

For more information

If you have any questions or comments about this advisory:

References

@ssddanbrown ssddanbrown published to BookStackApp/BookStack May 2, 2020
Reviewed May 7, 2020
Published to the GitHub Advisory Database May 7, 2020
Last updated Jan 9, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

EPSS score

0.079%
(35th percentile)

Weaknesses

CVE ID

CVE-2020-11055

GHSA ID

GHSA-5vf7-q87h-pg6w

Source code

No known source code
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