CVE-2026-0877

What it is

Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 147, Firefox ESR 115.32, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. High risk of data exposure, data tampering.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

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

Timeline

1. 2026-01-13 14:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-07-15 02:17 UTC Last updatedMost recent change to the record

Details

Published

2026-01-13 14:16 UTC

Last modified

2026-07-15 02:17 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-693

Record status

Modified

Affected

• Mozilla Firefox < 115.32.0
• Mozilla Firefox < 147.0
• Mozilla Firefox < 140.7.0
• Mozilla Thunderbird < 140.7.0
• Mozilla Thunderbird < 147.0

Attack profile CVSS 3.1 · 8.1

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None