CVE intelligence and bounded remediation
CVE-2020-25205 — Mimosa B5 Firmware security vulnerability
The web console for Mimosa B5, B5c, and C5x firmware through 2.8.0.2 is vulnerable to stored XSS in the set_banner() function of /var/www/core/controller/index.php. An unauthenticated attacker may set the contents of the /mnt/jffs2/banner.txt file, stored on the device's filesystem, to contain arbitrary JavaScript. The file contents are then used as part of a welcome/banner message presented to unauthenticated users who visit the login page for the web console. This vulnerability does not occur in the older 1.5.x firmware versions.
- Severity
- Medium
- CVSS
- 6.1 (3.1)
- Published
- 2021-07-20
- CISA KEV
- Not currently listed
- Ecosystem
- operating-system
- Weaknesses
- CWE-79
Affected products
- mimosa / b5_firmware
- mimosa / b5c_firmware
- mimosa / c5c_firmware
Matched remediation archetype
Cross-site scripting and unsafe browser output
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
Check exposure
- Trace reflected, stored, and DOM-derived untrusted values into HTML, attributes, URLs, styles, scripts, and client-side template sinks.
- Identify affected origins, authenticated user roles, sensitive browser capabilities, and where content is shared across tenants.
- Review framework escaping, rich-text sanitization, legacy templates, and client-side rendering paths.
Remediate safely
- Use context-aware framework output encoding and safe DOM APIs; keep untrusted data out of executable contexts.
- Sanitize intentionally supported markup with a maintained allowlist policy and validate URLs and attributes separately.
- Update affected rendering components and add tests for every output context using inert sentinel markup.
Authoritative sources
Complete CVE record and remediation plan
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