Mozilla Firefox up to 148 Fonts use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
8.5$5k-$25k0.09

Summaryinfo

A vulnerability marked as critical has been reported in Mozilla Firefox up to 148. This issue affects some unknown processing of the component Fonts. This manipulation causes use after free. This vulnerability is handled as CVE-2026-4696. The attack can be initiated remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Mozilla Firefox up to 148 and classified as critical. Affected by this vulnerability is an unknown code of the component Fonts. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Use-after-free in the Layout: Text and Fonts component. This vulnerability affects Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.

The advisory is shared at bugzilla.mozilla.org. This vulnerability is known as CVE-2026-4696 since 03/24/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 03/28/2026).

The vulnerability scanner Nessus provides a plugin with the ID 303906 (FreeBSD : Mozilla -- Multiple vulnerabilities (32819a60-2943-11f1-8461-b42e991fc52e)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 149 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (303906). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.6
VulDB Meta Temp Score: 8.5

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔒

ADP CISA Base Score: 9.8
ADP CISA Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 303906
Nessus Name: FreeBSD : Mozilla -- Multiple vulnerabilities (32819a60-2943-11f1-8461-b42e991fc52e)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Firefox 149

Timelineinfo

03/24/2026 Advisory disclosed
03/24/2026 +0 days CVE reserved
03/24/2026 +0 days VulDB entry created
03/28/2026 +4 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2026-4696 (🔒)
GCVE (CVE): GCVE-0-2026-4696
GCVE (VulDB): GCVE-100-352741

Entryinfo

Created: 03/24/2026 14:19
Updated: 03/28/2026 18:15
Changes: 03/24/2026 14:19 (56), 03/27/2026 19:37 (2), 03/28/2026 18:15 (22)
Complete: 🔍
Cache ID: 216:310:103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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