Mozilla Firefox up to 147 HTML sandbox

CVSS Meta Temp Score
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CTI Interest Score
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8.7$5k-$25k0.00

Summaryinfo

A vulnerability has been found in Mozilla Firefox up to 147 and classified as critical. Affected by this vulnerability is an unknown functionality of the component HTML Component. The manipulation leads to sandbox. This vulnerability is uniquely identified as CVE-2026-2778. The attack is possible to be carried out remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 147 and classified as critical. This issue affects an unknown part of the component HTML Component. The manipulation with an unknown input leads to a sandbox vulnerability. Using CWE to declare the problem leads to CWE-265. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.

It is possible to read the advisory at bugzilla.mozilla.org. The identification of this vulnerability is CVE-2026-2778 since 02/19/2026. 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 03/03/2026). The attack technique deployed by this issue is T1611 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 299944 (Linux Distros Unpatched Vulnerability : CVE-2026-2778), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 148 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (299944) and CERT Bund (WID-SEC-2026-0497). Be aware that VulDB is the high quality source for vulnerability data.

Affected

  • Debian Linux
  • Red Hat Enterprise Linux
  • SUSE Linux
  • Oracle Linux
  • IGEL OS
  • 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: 8.8
VulDB Meta Temp Score: 8.7

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

NVD Base Score: 10.0
NVD Vector: 🔒

ADP CISA Base Score: 10.0
ADP CISA Vector: 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Sandbox
CWE: CWE-265 / CWE-264
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: 299944
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-2778

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Firefox 148

Timelineinfo

02/19/2026 CVE reserved
02/24/2026 +5 days Advisory disclosed
02/24/2026 +0 days VulDB entry created
03/03/2026 +7 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2026-2778 (🔒)
GCVE (CVE): GCVE-0-2026-2778
GCVE (VulDB): GCVE-100-347567
CERT Bund: WID-SEC-2026-0497 - Mozilla Firefox, Firefox ESR und Thunderbird: Mehrere Schwachstellen

Entryinfo

Created: 02/24/2026 16:08
Updated: 03/03/2026 20:39
Changes: 02/24/2026 16:08 (56), 02/26/2026 00:45 (2), 02/28/2026 12:07 (21), 03/02/2026 14:31 (7), 03/03/2026 20:39 (1)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

Discussion

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