CVE-2026-74990 Mozilla — Exploit & Vulnerability Details CRITICAL

Parameter	Value
CVSS	9.8 (CRITICAL)
Affected Versions	116.0 — 153.1.0
Fixed In	115.39.0
Type	CWE-119 (Buffer Overflow)
Vendor	Mozilla
Public PoC	No

Internally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

Attack Parameters

Attack Vector

Network

Can be exploited remotely

Attack Complexity

Low

Easy to exploit

Privileges Required

None

No privileges needed

User Interaction

None

No user interaction needed

Impact Assessment

Confidentiality

High

Complete data leak

Integrity

High

Complete data modification

Availability

High

Complete denial of service

CVSS Vector v3.1

Weakness Type (CWE)

CWE-119 Buffer Overflow

Vulnerable Products 5

Configuration	From (including)	Up to (excluding)
Mozilla Firefox cpe:2.3:a:mozilla:firefox::::::::	—	`115.39.0`
Mozilla Firefox cpe:2.3:a:mozilla:firefox::::::::	`116.0`	`140.14.0`
Mozilla Firefox cpe:2.3:a:mozilla:firefox::::::::	`141.0`	`153.1.0`
Mozilla Thunderbird cpe:2.3:a:mozilla:thunderbird::::::::	—	`140.14.0`
Mozilla Thunderbird cpe:2.3:a:mozilla:thunderbird::::::::	`141.0`	`153.1.0`