CVE-2020-27224 Cross-site Scripting (XSS) in Eclipse Theia
Attackers can execute arbitrary code via the Markdown Preview feature in Eclipse Theia, posing a risk to developers using the IDE.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2020-27224?
CVE-2020-27224 is a critical cross-site scripting vulnerability in Eclipse Theia, published on 24 Feb 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
In Eclipse Theia versions up to and including 1.2.0, the Markdown Preview (@theia/preview), can be exploited to execute arbitrary code.
Weakness: CWE-79
Which versions are affected by CVE-2020-27224?
2 open source packages ship an affected version, including @theia/preview. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
@theia/preview npm | All versions | 1.3.0 |
@theia/preview npm | All versions | 1.3.0 |
Products include Eclipse Theia.
How do I fix CVE-2020-27224?
Upgrade @theia/preview to 1.3.0 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-2020-27224 being exploited?
There is no known exploitation of CVE-2020-27224 in the wild and no public exploit code.
Other vulnerabilities in Eclipse Theia
- CVE-2021-34436 XML external entity in Eclipse Theia
- CVE-2026-60009 File upload in Eclipse Theia
- CVE-2021-34435 Remote code execution in Eclipse Theia
- CVE-2026-44688 [Eclipse Theia] Indirect Prompt Injection via Adversarial Workspace File and Directory Names in AI Chat
- CVE-2026-44691 [Eclipse Theia] Arbitrary Command Execution via Untrusted Workspace Task Definitions
Sources
Also known as GHSA-gcm9-cc3r-c6vj.