Cross-Site Scripting (XSS) in openc3 (CVE-2026-42086)
Summary
Cross-site scripting in openc3 (CVE-2026-42086). Risk of unauthorized operations or information disclosure. Exploitable via convertToValue. Mitigation: upgrade to 7.0.0 or later.
Original description
The description as published by the source.
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
- Using a drop-down form, choose any command that supports ARRAY parameters,
- Inside square brackets “[…]” place a JavaScript code to be executed
- Send command to CmdTlmServer using dedicated “Send” button
- Observe JavaScript code being executed in the current browser session context
Below example uses INST ARYCMD to execute simple JavaScript code snippet alert(“XSS”).
Impact
Local JavaScript execution in the user's browser
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-42086 has been found in openc3.
Attackers can target a specific entry point like convertToValue over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.6/10.
What to do: upgrade openc3 to 7.0.0 or later.
If unsure, ask your IT team or search "openc3 CVE-2026-42086" on the vendor's site.
CVE-2026-42086 (openc3) — CWE-79 / CVSS v3 4.6
Attack vector: remote (network-reachable)
Attack surface: convertToValue
Patched: 7.0.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Cross-site scripting (XSS) (CWE-79) exists in openc3. Attackers reach the vulnerable code path via convertToValue.
Check the vendor advisory for the affected versions of openc3. Attack surface: convertToValue.
Severity: Medium (CVSS 4.6/10). Risk of unauthorized operations or information disclosure.
Update to 7.0.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'openc3' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'openc3' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
openc3を grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade openc3 to 7.0.0ステージング環境で 7.0.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com