CVE-2021-34435

mediumpriority · track · 35EPSS 0.006 · 48 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.60% (48th) EPSS

CVSS 6.8 · medium

Is it mine?

4 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · nvd · osv

EPSS · scored 2026-10-27

In Eclipse Theia 0.3.9 to 1.8.1, the "mini-browser" extension allows a user to preview HTML files in an iframe inside the IDE. But with the way it is made it is possible for a previewed HTML file to trigger an RCE. This exploit only happens if a user previews a malicious file..

cvss

Technical severity, 0–10. One row per scoring source.

8.8

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.8–8.8

v2.06.8mediumAV:N/AC:M/Au:N/C:P/I:P/A:Pprimary · NVD / NIST USexploitability 8.6 · impact 6.4

v3.18.8highCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 2.8 · impact 5.9

v3.18.8highCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · OSV

v3.18.1highCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-346USprimaryCWE-346USCWE-668USCWE-942USCWE-942US

affected products (4)

Products and version ranges known to be affected.

The Eclipse Foundation Eclipse Theia≤ unspecified ≤1.8.1enisa_euvdEU
The Eclipse Foundation Eclipse Theia0.3.9 → unspecifiedenisa_euvdEU
eclipse theia0.3.9 → 1.8.1nvdUScpe:2.3:a:eclipse:theia:*:*:*:*:*:*:*:*
npm @theia/mini-browser0.3.9 → 1.9.0osvUSpkg:npm/%40theia/mini-browser

advisories (1)

Vendor and ecosystem advisories describing this.

GHSA-v9w2-v7j9-rjprRemote code execution in Eclipse Theia2021-09-02ghsa · osvUS
In Eclipse Theia 0.3.9 to 1.8.1, the "mini-browser" extension allows a user to preview HTML files in an iframe inside the IDE. But with the way it is made it is possible for a previewed HTML file to trigger an RCE. This exploit only happens if a user previews a malicious file.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd osv NVD CVE.org MITRE

published 2021-09-01modified 2026-06-17

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references (4)

External citations — patches, advisories, analysis.

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