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MEDIUM severity

CVE-2021-28161 — @theia/console

MEDIUM

CVE-2021-28161 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in @theia/console. 1 public exploit reference exists, so weaponization risk is real. A fix is available for @theia/console — see the affected versions and patch details below.

Improper Neutralization of Input in Theia console

Also known asGHSA-cwg9-c9cr-p5fq
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs52th percentile — riskier than 52% of all scored CVEsHighest risk
0.00%0.40%0.81%1.21%0.2%0.7%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-28161 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

5other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
@theia/consolenpm
22Kdownloads / week

Description

In Eclipse Theia versions up to and including 1.8.0, in the debug console there is no HTML escaping, so arbitrary Javascript code can be injected.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npm@theia/consoleall versions1.8.1npm install @theia/console@1.8.1

Affected Products

1 product · 1 configurations
Application
theiaeclipse
≤ 1.8.0
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

In Eclipse Theia versions up to and including 1.8.0, in the debug consol…

github.comNVDMar 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @theia/console, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update @theia/console to 1.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-28161 is resolved across your whole dependency graph.

  3. Workarounds

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

In Eclipse Theia versions up to and including 1.8.0, in the debug console there is no HTML escaping, so arbitrary Javascript code can be injected.
O3 Security · Impact-Aware SCA

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CVE-2021-28161: @theia/console — Fixed in 1.8.1