What is CVE-2021-41038?

CVE-2021-41038 is a medium-severity vulnerability in Eclipse Theia, classified under Improper Verification of Source of a Communication Channel. CVSS score: 6.1/10. Published 2021-11-10.

How severe is CVE-2021-41038?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Vulnerability in Eclipse Theia

CVE-2021-41038

In versions of the @theia/plugin-ext component of Eclipse Theia prior to 1.18.0, Webview contents can be hijacked via postMessage().

Published 2021-11-10 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.007 (52.7th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 52.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: +0.000

Affected products

Eclipse Theia
The Eclipse Foundation @Theia/plugin-Ext — versions unspecified

Weakness classification (CWE)

CWE-940 — Improper Verification of Source of a Communication Channel

References

bugs.eclipse.org/bugs/show_bug.cgi (Exploit, Third Party Advisory, Issue Tracking)
github.com/eclipse-theia/theia/pull/10125 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-41038?: CVE-2021-41038 is a medium-severity vulnerability in Eclipse Theia, classified under Improper Verification of Source of a Communication Channel. CVSS score: 6.1/10. Published 2021-11-10.
How severe is CVE-2021-41038?: Medium severity. CVSS v3 base score is 6.1 out of 10.