CVE-2021-39946 Cross-site scripting in GitLab

High 8.7 Published 18 Jan 2022 Updated 4 Aug 2024

An attacker can execute arbitrary scripts in victim browsers via emoji HTML generation, potentially leading to session hijacking or data theft.

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-2021-39946?

CVE-2021-39946 is a high-severity cross-site scripting vulnerability in Gitlab Gitlab, published on 18 Jan 2022. 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 neutralization of user input in GitLab CE/EE versions 14.3 to 14.3.6, 14.4 to 14.4.4, and 14.5 to 14.5.2 allowed an attacker to exploit XSS by abusing the generation of the HTML code related to emojis

Weakness: CWE-79

Which versions are affected by CVE-2021-39946?

1 open source package ship an affected version, including gitlab. It affects 1 product.

Package	Affected	Fixed in
`gitlab` Bitnami	From `14.3.0`	`14.3.6, 14.4.4, 14.5.2`

Products include Gitlab Gitlab.

How do I fix CVE-2021-39946?

Upgrade gitlab to a fixed version for your release line: 14.3.6, 14.4.4 or 14.5.2.

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-2021-39946 being exploited?

There is no known exploitation of CVE-2021-39946 in the wild and no public exploit code.

All Gitlab Gitlab vulnerabilities

Sources

Also known as BIT-gitlab-2021-39946, GHSA-rvcw-fpwr-r263, UBUNTU-CVE-2021-39946.