CVE-2026-25789
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedAffected devices do not properly validate and sanitize filenames on the Firmware Update page. This could allow a remote attacker to social engineer the user into selecting the modified firmware file to be uploaded. This would result in malitcious JavaScript execution in the context of the authenticated user's session without requiring the file to be uploaded, potentially leading to session hijacking or credential theft.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceThis is a stored XSS vulnerability on the Firmware Update page where the device fails to validate and sanitize filenames. An attacker social engineers a user into selecting a maliciously-named firmware file, causing JavaScript to execute in the authenticated user's browser context upon file selection (before actual upload), enabling session hijacking or credential theft.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- Low
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Locate the firmware update interfaceNavigate to the device's administrative web interface and search for sections labeled 'Firmware', 'Update', 'Upgrade', or 'System Maintenance'. Identify if a firmware upload or file selection input exists.Affected if The device provides a web-based firmware update feature with a file selection input.
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Inspect the file input HTML sourceRight-click the firmware upload page and view the page source (or use browser developer tools). Examine the <input type='file'> element and surrounding markup for any client-side filename validation or encoding.Affected if The HTML displays or reflects the selected filename without HTML entity encoding (e.g., shows raw filename in an element that updates on file selection).
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Test filename reflection in the browserOn the firmware update page, click 'Choose File' and observe how the selected filename is displayed in the UI. Check if special characters like <, >, ', or " in a test filename appear rendered as-is or as HTML entities.Affected if The filename appears as plain text with potentially executable characters (such as <script> tags) visible or the UI updates to show the raw filename without sanitization.
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Check for Content Security Policy headersUse browser developer tools (Network tab) to inspect HTTP response headers from the firmware update page. Look for a 'Content-Security-Policy' header and examine its directives, particularly 'script-src' and 'unsafe-inline'.Affected if No CSP header is present, or CSP allows 'unsafe-inline' without other mitigations, leaving the page vulnerable to XSS execution.
A user is affected if their device firmware update page displays or reflects the selected filename in the browser without HTML encoding and lacks a restrictive Content Security Policy, allowing injected script tags in a maliciously-named firmware file to execute upon file selection.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataImplement strict filename validation and sanitization on the firmware upload page, including allowlist filtering and HTML encoding of displayed filenames. Additionally, implement Content Security Policy (CSP) headers to mitigate XSS execution.
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-25789 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-25789 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data