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MEDIUM severity

GHSA-5vf7-q87h-pg6w ssddanbrown/bookstack

MEDIUM

GHSA-5vf7-q87h-pg6w is a medium-severity (CVSS 6.3) 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 asCVE-2020-11055
Published
May 7, 2020
Updated
Sep 10, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Sep 19, 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 CVEs54th percentile — riskier than 54% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

GHSA-5vf7-q87h-pg6w plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.

Where this sits among everything scored

Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

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/bookstack0.18.0&&< 0.29.20.29.2composer require ssddanbrown/bookstack:^0.29.2

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 GHSA-5vf7-q87h-pg6w is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-5vf7-q87h-pg6w can be triaged on real exposure rather than presence alone.

Tailored to GHSA-5vf7-q87h-pg6w. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

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 GHSA-5vf7-q87h-pg6w in your dependencies?

O3 Security finds GHSA-5vf7-q87h-pg6w across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

GHSA-5vf7-q87h-pg6w: Medium 6.3 severity | O3 Security