Mozilla Firefox up to 146 protection mechanism

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-$25k0.00

Summaryinfo

A vulnerability was found in Mozilla Firefox up to 146. It has been rated as critical. Affected by this vulnerability is an unknown functionality. The manipulation leads to Remote Code Execution. This vulnerability is documented as CVE-2026-0877. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Mozilla Firefox up to 146. This issue affects an unknown function. The manipulation with an unknown input leads to a remote code execution vulnerability. Using CWE to declare the problem leads to CWE-693. The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Mitigation bypass in the DOM: Security component. This vulnerability affects Firefox < 147, Firefox ESR < 115.32, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.

It is possible to read the advisory at bugzilla.mozilla.org. The identification of this vulnerability is CVE-2026-0877 since 01/13/2026. 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. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 01/22/2026).

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). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

  • Debian Linux
  • Red Hat Enterprise 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
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Protection mechanism
CWE: CWE-693
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
01/22/2026 +9 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2026-0877 (🔒)
GCVE (CVE): GCVE-0-2026-0877
GCVE (VulDB): GCVE-100-340571
CERT Bund: WID-SEC-2026-0090 - Mozilla Firefox und Thunderbird: Mehrere Schwachstellen

Entryinfo

Created: 01/13/2026 15:16
Updated: 01/22/2026 10:53
Changes: 01/13/2026 15:16 (53), 01/15/2026 16:23 (3), 01/15/2026 18:19 (2), 01/15/2026 21:19 (7), 01/22/2026 10:53 (1)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Discussion

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