Mozilla Firefox up to 153.4/157 WebAssembly comparing

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
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-$25k0.00-

Summaryinfo

A vulnerability classified as critical was found in Mozilla Firefox up to 153.4/157. Affected by this issue is some unknown functionality of the component WebAssembly. Executing a manipulation can lead to comparing. This vulnerability is registered as CVE-2026-109720. It is possible to launch the attack remotely. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in Mozilla Firefox up to 153.4/157 and classified as critical. This vulnerability affects an unknown function of the component WebAssembly. The manipulation with an unknown input leads to a comparing vulnerability. The CWE definition for the vulnerability is CWE-482. The code uses an operator for comparison when the intention was to perform an assignment. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

JIT miscompilation in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 158 and Firefox ESR 153.5.

The advisory is available at bugzilla.mozilla.org. This vulnerability was named CVE-2026-109720 since 10/13/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 10/13/2026).

Upgrading to version 153.5 or 158 eliminates this vulnerability.

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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: Comparing
CWE: CWE-482
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 153.5/158

Timelineinfo

10/13/2026 Advisory disclosed
10/13/2026 +0 days CVE reserved
10/13/2026 +0 days VulDB entry created
10/13/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2026-109720 (🔒)
GCVE (CVE): GCVE-0-2026-109720
GCVE (VulDB): GCVE-100-417550

Entryinfo

Created: 10/13/2026 15:03
Changes: 10/13/2026 15:03 (57)
Complete: 🔍
Cache ID: 216::103

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