CVE-2021-34436 XML external entity in Eclipse Theia
Attackers can achieve remote code execution and read sensitive data via XML External Entity injection in the default XML extension of Eclipse Theia.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-34436?
CVE-2021-34436 is a critical vulnerability in Eclipse Theia, published on 2 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In Eclipse Theia 0.1.1 to 0.2.0, it is possible to exploit the default build to obtain remote code execution (and XXE) via the theia-xml-extension. This extension uses lsp4xml (recently renamed to LemMinX) in order to provide language support for XML. This is installed by default.
Which versions are affected by CVE-2021-34436?
It affects 1 product.
Products include Eclipse Theia.
How do I fix CVE-2021-34436?
No fix has been published for CVE-2021-34436 yet. Limit exposure of the affected software until one is available.
Is CVE-2021-34436 being exploited?
There is no known exploitation of CVE-2021-34436 in the wild and no public exploit code.
Other vulnerabilities in Eclipse Theia
- CVE-2020-27224 Cross-site Scripting (XSS) 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-8gpx-73gc-wq7c.