CVE-2026-2761: Critical – Sandbox escape in the Graphics: WebRender component. This

A critical vulnerability, CVE-2026-2761, exists in the Graphics: WebRender component of Firefox and Thunderbird, allowing for a sandbox escape. This could lead to arbitrary code execution with the privileges of the browser.

BSID: BS-2026-GLOBAL-079192-C • Model: /workspace/models/qwen2.5-coder-32b-instruct-bf16 • Confidence: HIGH

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Frequently Asked Questions

What is CVE-2026-2761?

A critical vulnerability, CVE-2026-2761, exists in the Graphics: WebRender component of Firefox and Thunderbird, allowing for a sandbox escape. This could lead to arbitrary code execution with the privileges of the browser.

What is the CVSS score for CVE-2026-2761?

CVE-2026-2761 has CVSS 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H. EPSS: 0.6%.

Is CVE-2026-2761 actively exploited?

No confirmed active exploitation of CVE-2026-2761 as of 2026-09-25.

How do I remediate CVE-2026-2761?

Priority: IMMEDIATE. Advisory: https://www.mozilla.org/security/advisories/mfsa2026-13/ PSIRT: [email protected]

What systems are affected by CVE-2026-2761?

CVE-2026-2761 affects Mozilla Firefox, Thunderbird.

Vulnerability Details

CVE ID	`CVE-2026-2761`
BSID	`BS-2026-GLOBAL-079192-C` BreachSpider Global ID
CVSS Vector	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`
Published	2026-02-24
Last Modified	2026-07-15
ICS Relevance	0%
Weakness (CWE)	CWE-693
Source	NVD

Official Description

Sandbox escape in the Graphics: WebRender component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Source: NIST NVD / MITRE CVE Database

Attack Vector Analysis — CITED Relevance

An attacker could exploit this vulnerability by crafting a malicious web page that, when visited, could escape the browser's sandbox and execute arbitrary code on the user's system.

Exploitation Likelihood: CRITICAL

Affected Products

Vendor	Product	Affected Versions
Mozilla	Firefox	`< 148.0`
Mozilla	Thunderbird	`< 148.0`

Remediation

View Vendor Advisory →

Remediation Priority: IMMEDIATE

Vendor PSIRT: [email protected]

Threat Intelligence

● Threat Intelligence Validated: October 2026 | Threat Age: 233 Days

CISA known-exploited	Not in KEV catalog
Public Exploit	Not confirmed
PoC Code	Not confirmed

AI Enrichment Record — provenance & audit hash

Model	`/workspace/models/qwen2.5-coder-32b-instruct-bf16`
Confidence	HIGH
Enriched At	2026-05-24
SHA-512 Audit Hash	`56af547e761b353dc28b181392e58f82ba8615dee886bf17903a5e7c9a8cf71bbc1eda21c07e36d067408ca461b7c9acf98d32d4ce5e902dd3be2ea1cc123db7`

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