CVE-2013-0776

What it is

Mozilla Firefox before 19.0, Firefox ESR 17.x before 17.0.3, Thunderbird before 17.0.3, Thunderbird ESR 17.x before 17.0.3, and SeaMonkey before 2.16 allow man-in-the-middle attackers to spoof the address bar by operating a proxy server that provides a 407 HTTP status code accompanied by web script, as demonstrated by a phishing attack on an HTTPS site.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

1.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2013-02-19 23:55 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-16 23:50 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.3% in the next 30 days (EPSS).
• Severity: 4.0 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2013-02-19 23:55 UTC

Last modified

2026-06-16 23:50 UTC

Exploit probability

1.3% · EPSS, next 30 days

Weakness

CWE-295 · Improper certificate validation

Record status

Modified

Affected

• Mozilla Firefox < 17.0.3
• Mozilla Firefox < 19.0
• Mozilla Seamonkey < 2.16
• Mozilla Thunderbird < 17.0.3
• Mozilla Thunderbird Esr < 17.0.3
• Opensuse 11.4
• Opensuse 12.1
• Opensuse 12.2

Attack profile CVSS 2.0 · 4.0

Attack vector

Network

Complexity

High

Authentication

None

Confidentiality

Partial

Integrity

Partial

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2013-0776.md and follow it. Check whether this project is affected by CVE-2013-0776. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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