Cyber Posture

CVE-2026-2770

Critical

Published: 24 February 2026

Published
24 February 2026
Modified
13 April 2026
KEV Added
—
Patch
—
CVSS Score 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0002 4.9th percentile
Risk Priority 20 60% EPSS · 20% KEV · 20% CVSS

Description

Use-after-free in the DOM: Bindings (WebIDL) component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match
prevent

Requires timely remediation of identified flaws through patching, directly addressing the use-after-free vulnerability fixed in updated Firefox and Thunderbird versions.

RA-5 Vulnerability Monitoring and Scanning partial match
detect

Enables vulnerability scanning to identify systems running vulnerable Firefox or Thunderbird versions affected by this CVE.

SI-16 Memory Protection partial match
prevent

Implements memory protection mechanisms like ASLR and DEP to mitigate exploitation of the use-after-free vulnerability in the browser's DOM bindings.

Security SummaryAI

CVE-2026-2770 is a use-after-free vulnerability (CWE-416) in the DOM: Bindings (WebIDL) component of Mozilla Firefox and Thunderbird. It affects versions of Firefox prior to 148, Firefox ESR prior to 115.33 and 140.8, and Thunderbird prior to 148 and 140.8. The issue was publicly disclosed on 2026-02-24 and carries a CVSS v3.1 base score of 9.8, indicating critical severity due to its potential for high-impact exploitation.

Remote attackers require no privileges or user interaction to exploit this vulnerability over the network with low attack complexity and no scope change. Successful exploitation could result in high confidentiality, integrity, and availability impacts, potentially allowing arbitrary code execution within the browser's rendering engine.

Mozilla's security advisories (MFSA 2026-13 through 2026-16) and Bugzilla entry 2014585 confirm the vulnerability was addressed in the specified fixed releases. Security practitioners should prioritize updating affected Firefox and Thunderbird installations to the patched versions to mitigate the risk.

Details

CWE(s)
CWE-416

Affected Products

mozilla
firefox
≤ 115.33.0 · ≤ 148.0 · 128.0 — 140.8.0
mozilla
thunderbird
≤ 140.8.0 · ≤ 148.0

MITRE ATT&CK Enterprise TechniquesAI

T1189 Drive-by Compromise Initial Access
Adversaries may gain access to a system through a user visiting a website over the normal course of browsing.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
Why these techniques?

Use-after-free in browser DOM/WebIDL enables remote arbitrary code execution (no user interaction) via malicious web content, directly mapping to drive-by initial access and client-side exploitation for execution.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

References