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Mozilla, Multiple Products
Description
Mozilla Firefox, SeaMonkey, and Thunderbird contain an unspecified vulnerability when JavaScript is enabled. This allows remote attackers to execute arbitrary code via vectors related to nsCSSFrameConstructor::ContentAppended, the appendChild method, incorrect index tracking, and the creation of multiple frames, which triggers memory corruption.
CVSS severity
Critical (9.8/10)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Sourced from NVD, reflects how severe this vulnerability is if exploited, not whether it has been. Every advisory on this page is already a CISA-confirmed active exploitation case regardless of its CVSS score.
EPSS, exploit probability
Critical83.2%
estimated chance of real-world exploitation in the next 30 days, higher than 99.7% of every CVE FIRST.org scores
Refreshed 10/28/2026, via FIRST.org's EPSS model, not CVSS, this measures likelihood of exploitation, not how severe it would be.
Public exploit references (via NVD)
Required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA-recommended due date: 2025-10-27
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