Is CVE-2021-34436 actively exploited?

No active exploitation of CVE-2021-34436 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-34436 be exploited remotely?

Yes. CVE-2021-34436 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-34436?

CVE-2021-34436 has a CVSS score of 9.8 (CRITICAL).

HOME VULNERABILITIESCVE-2021-34436

CRITICAL

CVE-2021-34436

CWE-22Published: September 2, 2021· Updated: Jun 17, 2026

9.8

CVSS v3.1

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.

NVD Source

Technical Analysis

CVE-2021-34436 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.