# CVE-2026-84695: BookStack before 26.05.4 Stored XSS via Drawing Upload

> Attackers with editor permissions can inject scripts via SVG uploads that execute in administrator browsers, potentially leading to account takeover.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 2 Sep 2026
- **Updated:** 2 Sep 2026
- **Also known as:** GHSA-r46q-wv4x-rj72

## What is CVE-2026-84695?

CVE-2026-84695 is a critical cross-site scripting vulnerability in bookstackapp bookstack, published on 2 Sep 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

BookStack before 26.05.4 contains a stored cross-site scripting vulnerability in the drawing upload endpoint that accepts unvalidated base64 content and stores it without content inspection. Attackers with editor permissions can upload SVG files containing scripts that execute in administrator browsers when accessed through the image gallery API without content-type validation or CSP headers.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-84695?


## How do I fix CVE-2026-84695?

No fix has been published for CVE-2026-84695 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-84695 being exploited?

There is no known exploitation of CVE-2026-84695 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-84695 and fix it if it is affected.

What it is: CVE-2026-84695 is a critical cross-site scripting vulnerability in bookstackapp bookstack, published on 2 Sep 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-84695 in the wild and no public exploit code.

Affected product: bookstackapp bookstack. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-84695/ (Markdown: https://insights.sbomify.com/CVE-2026-84695/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-84695
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-84695
- OSV: https://osv.dev/vulnerability/CVE-2026-84695

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-84695/
Summaries are generated and may contain mistakes; the official description above is the record.