Mozilla Firefox up to 146 JavaScript Engine use after free

CVSS Meta Temp Score
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CTI Interest Score
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6.0$5k-$25k0.94

Summaryinfo

A vulnerability was found in Mozilla Firefox up to 146. It has been rated as critical. This vulnerability affects unknown code of the component JavaScript Engine. This manipulation causes use after free. This vulnerability is registered as CVE-2026-0884. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 146. It has been declared as critical. Affected by this vulnerability is an unknown function of the component JavaScript Engine. 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 JavaScript Engine component. This vulnerability affects Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.

The advisory is shared at bugzilla.mozilla.org. This vulnerability is known as CVE-2026-0884 since 01/13/2026. 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 06/11/2026).

The vulnerability scanner Nessus provides a plugin with the ID 284821 (RHEL 8 : firefox (RHSA-2026:0667)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 147 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (284821) and CERT Bund (WID-SEC-2026-0090). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Mozilla Firefox
  • Mozilla Firefox ESR
  • Mozilla Thunderbird

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
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
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: 284821
Nessus Name: RHEL 8 : firefox (RHSA-2026:0667)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Firefox 147

Timelineinfo

01/13/2026 Advisory disclosed
01/13/2026 +0 days CVE reserved
01/13/2026 +0 days VulDB entry created
06/11/2026 +149 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2026-0884 (🔒)
GCVE (CVE): GCVE-0-2026-0884
GCVE (VulDB): GCVE-100-340585
CERT Bund: WID-SEC-2026-0090 - Mozilla Firefox und Thunderbird: Mehrere Schwachstellen

Entryinfo

Created: 01/13/2026 15:21
Updated: 06/11/2026 19:54
Changes: 01/13/2026 15:21 (56), 01/15/2026 17:13 (1), 01/15/2026 18:19 (2), 01/15/2026 21:47 (7), 01/23/2026 01:41 (1), 06/11/2026 19:54 (1)
Complete: 🔍
Cache ID: 216::103

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

Discussion

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