CVE-2021-21660 XSS vulnerability in Jenkins Markdown Formatter Plugin
Attackers with edit permissions can inject malicious scripts via crafted URLs in Markdown descriptions, leading to stored XSS attacks against Jenkins users.
- 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-2021-21660?
CVE-2021-21660 is a medium-severity cross-site scripting vulnerability in Jenkins Markdown Formatter Plugin, published on 25 May 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
Jenkins Markdown Formatter Plugin 0.1.0 and earlier does not sanitize crafted link target URLs, resulting in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with the ability to edit any description rendered using the configured markup formatter.
Weakness: CWE-79
Which versions are affected by CVE-2021-21660?
2 open source packages ship an affected version, including io.jenkins.plugins:markdown-formatter. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
io.jenkins.plugins:markdown-formatter Maven | All versions | 0.2.0 |
io.jenkins.plugins:markdown-formatter Maven | All versions | 0.2.0 |
Products include Jenkins Markdown Formatter.
How do I fix CVE-2021-21660?
Upgrade io.jenkins.plugins:markdown-formatter to 0.2.0 or later.
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-2021-21660 being exploited?
There is no known exploitation of CVE-2021-21660 in the wild and no public exploit code.
Sources
Also known as GHSA-xqpp-26pp-2365.