Mozilla Firefox up to 115.39/140.14/153.1/154 Audio/Video use after free

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 115.39/140.14/153.1/154. Impacted is an unknown function of the component Audio/Video. Executing a manipulation can lead to use after free. This vulnerability is registered as CVE-2026-84120. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 115.39/140.14/153.1/154. It has been declared as critical. This vulnerability affects an unknown function of the component Audio/Video. 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. CVE summarizes:

Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2.

The advisory is shared for download at bugzilla.mozilla.org. This vulnerability was named CVE-2026-84120 since 09/01/2026. 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. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 09/01/2026).

Upgrading to version 115.40, 140.15, 153.2 or 155 eliminates this vulnerability.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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 115.40/140.15/153.2/155

Timelineinfo

09/01/2026 Advisory disclosed
09/01/2026 +0 days CVE reserved
09/01/2026 +0 days VulDB entry created
09/01/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2026-84120 (🔒)
GCVE (CVE): GCVE-0-2026-84120
GCVE (VulDB): GCVE-100-397600

Entryinfo

Created: 09/01/2026 14:55
Changes: 09/01/2026 14:55 (57)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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