NIST deprecates RSA-2048 from 2030. Find every one of them before attackers do.
🐘
🐘 Packagist
Not in CISA KEV
MEDIUM severity

CVE-2020-11055 — bookstack

MEDIUM

CVE-2020-11055 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in ssddanbrown/bookstack. A fix is available for ssddanbrown/bookstack — see the affected versions and patch details below.

Cross-Site Scripting in BookStack

Also known asGHSA-5vf7-q87h-pg6w
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 1, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.8%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs56th percentile — riskier than 56% of all scored CVEsHighest risk
0.00%0.43%0.85%1.28%0.4%0.8%May 26Aug 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐘ssddanbrown/bookstack

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

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:

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistssddanbrown/bookstack≥ 0.18.0&&< 0.29.20.29.2composer require ssddanbrown/bookstack:^0.29.2

Affected Products

1 product · 1 configurations
Application
bookstackbookstackapp
≥ 0.18.0 && < 0.29.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ssddanbrown/bookstack, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update ssddanbrown/bookstack to 0.29.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-11055 is resolved across your whole dependency graph.

  3. Workarounds

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

### 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.
O3 Security · Impact-Aware SCA

Is CVE-2020-11055 in your dependencies?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works
CVE-2020-11055: bookstack — Fixed in 0.29.2