CVE-2021-39906 Cross-site scripting in GitLab
An attacker can execute arbitrary JavaScript code on a victim's behalf via improperly validated ipynb files in GitLab.
- 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
What is CVE-2021-39906?
CVE-2021-39906 is a high-severity cross-site scripting vulnerability in Gitlab Gitlab, published on 4 Nov 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Improper validation of ipynb files in GitLab CE/EE version 13.5 and above allows an attacker to execute arbitrary JavaScript code on the victim's behalf.
Weakness: CWE-79
Which versions are affected by CVE-2021-39906?
1 open source package ship an affected version, including gitlab. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
gitlab Bitnami | From 13.5.0 | 14.2.6, 14.3.4, 14.4.1 |
Products include Gitlab Gitlab.
How do I fix CVE-2021-39906?
Upgrade gitlab to a fixed version for your release line: 14.2.6, 14.3.4 or 14.4.1.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2021-39906 being exploited?
There is no known exploitation of CVE-2021-39906 in the wild and no public exploit code.
Other vulnerabilities in Gitlab Gitlab
- CVE-2026-97229 GitLab Community Edition and Enterprise Edition Integer Overflow or Wraparound
- CVE-2026-85706 GitLab Community Edition and Enterprise Edition Path Traversal
- CVE-2023-7028 GitLab Community and Enterprise Editions Improper Access Control
- CVE-2021-22205 GitLab Community and Enterprise Editions Remote Code Execution
- CVE-2021-39935 GitLab Community and Enterprise Editions Server-Side Request Forgery (SSRF)
Sources
Also known as BIT-gitlab-2021-39906, GHSA-6cxq-rcp9-rqr8, UBUNTU-CVE-2021-39906.