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MEDIUM severity

GHSA-ffq5-qpvf-xq7x — openc3

MEDIUM

GHSA-ffq5-qpvf-xq7x is a medium-severity (CVSS 4.6) Cross-site Scripting (XSS) vulnerability in openc3. A fix is available for openc3 — see the affected versions and patch details below.

OpenC3 COSMOS is Vulnerable to Self-XSS Through the Command Sender

Also known asCVE-2026-42086PYSEC-2026-105
Published
Apr 22, 2026
Updated
May 29, 2026
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Sep 24, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for GHSA-ffq5-qpvf-xq7x.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs19th percentile — riskier than 19% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

GHSA-ffq5-qpvf-xq7x plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.

Where this sits among everything scored

Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

Real-World Exposure

2 pkgs affected
🐍openc3💎openc3

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI, RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

Summary

The Command Sender UI uses an unsafe eval() function on array-like command parameters, which allows a user-supplied payload to execute in the browser when sending a command. This creates a self-XSS risk because an attacker can trigger their own script execution in the victim’s session, if allowed to influence the array parameter input, for example via phishing. If successful, an attacker may read or modify data in the authenticated browser context, including session tokens in local storage.

Details

The unsafe eval() usage on user-supplied ARRAY parameters happens in convertToValue method in CommandSender.vue

PoC

  1. Using a drop-down form, choose any command that supports ARRAY parameters,
  2. Inside square brackets “[…]” place a JavaScript code to be executed
  3. Send command to CmdTlmServer using dedicated “Send” button
  4. Observe JavaScript code being executed in the current browser session context

Below example uses INST ARYCMD to execute simple JavaScript code snippet alert(“XSS”). <img width="947" height="356" alt="image" src="https://github.com/user-attachments/assets/6fbdb6c9-616a-4268-bbb8-a8a1044437ad" />

<img width="942" height="545" alt="image" src="https://github.com/user-attachments/assets/4df24353-aea0-4aa0-adcf-b7c7e387dc83" />

Impact

Local JavaScript execution in the user's browser

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIopenc3all versions7.0.0pip install --upgrade 'openc3==7.0.0'
💎RubyGemsopenc3all versions7.0.0bundle update openc3 --conservative

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openc3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update openc3 to 7.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-ffq5-qpvf-xq7x is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-ffq5-qpvf-xq7x can be triaged on real exposure rather than presence alone.

Tailored to GHSA-ffq5-qpvf-xq7x. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary The Command Sender UI uses an unsafe `eval()` function on array-like command parameters, which allows a user-supplied payload to execute in the browser when sending a command. This creates a self-XSS risk because an attacker can trigger their own script execution in the victim’s session, if allowed to influence the array parameter input, for example via phishing. If successful, an attacker may read or modify data in the authenticated browser context, including session tokens in local storage. ### Details The unsafe `eval()` usage on user-supplied ARRAY parameters happens in `conv
O3 Security · Impact-Aware SCA

Is GHSA-ffq5-qpvf-xq7x in your dependencies?

O3 Security finds GHSA-ffq5-qpvf-xq7x across PyPI, RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works
GHSA-ffq5-qpvf-xq7x: openc3 (Medium 4.6) | O3 Security