Mozilla Firefox up to 115.41/140.16/153.3/156 Layout Text/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.
6.0$5k-$25k0.54+

Summaryinfo

A vulnerability was found in Mozilla Firefox up to 115.41/140.16/153.3/156. It has been classified as critical. This affects an unknown function of the component Layout Text/Fonts. The manipulation leads to use after free. This vulnerability is listed as CVE-2026-100784. The attack may be initiated remotely. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 115.41/140.16/153.3/156. It has been rated as critical. This issue affects an unknown code block of the component Layout Text/Fonts. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Use-after-free in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

The advisory is shared at bugzilla.mozilla.org. The identification of this vulnerability is CVE-2026-100784 since 09/26/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. 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 09/29/2026).

Upgrading to version 115.42, 140.17, 153.4 or 157 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.0

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

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
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Firefox 115.42/140.17/153.4/157

Timelineinfo

09/26/2026 CVE reserved
09/29/2026 +3 days Advisory disclosed
09/29/2026 +0 days VulDB entry created
09/29/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2026-100784 (🔒)
GCVE (CVE): GCVE-0-2026-100784
GCVE (VulDB): GCVE-100-411353

Entryinfo

Created: 09/29/2026 15:25
Changes: 09/29/2026 15:25 (57)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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