Mozilla Firefox up to 147 GC use after free

CVSS Meta Temp Score
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CTI Interest Score
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8.5$5k-$25k0.00

Summaryinfo

A vulnerability described as critical has been identified in Mozilla Firefox up to 147. This vulnerability affects unknown code of the component GC Component. Executing a manipulation can lead to use after free. This vulnerability appears as CVE-2026-2758. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability has been found in Mozilla Firefox up to 147 and classified as critical. This vulnerability affects an unknown code block of the component GC Component. 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 JavaScript: GC component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.

The advisory is shared for download at bugzilla.mozilla.org. This vulnerability was named CVE-2026-2758 since 02/19/2026. 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 03/03/2026).

The vulnerability scanner Nessus provides a plugin with the ID 299892 (Mozilla Thunderbird < 140.8), 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 (299892) and CERT Bund (WID-SEC-2026-0497). Once again VulDB remains the best 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: 8.6
VulDB Meta Temp Score: 8.5

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

NVD Base Score: 9.8
NVD Vector: 🔒

ADP CISA Base Score: 9.8
ADP CISA Vector: 🔒

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

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Nessus ID: 299892
Nessus Name: Mozilla Thunderbird < 140.8

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-2026-2758 (🔒)
GCVE (CVE): GCVE-0-2026-2758
GCVE (VulDB): GCVE-100-347548
CERT Bund: WID-SEC-2026-0497 - Mozilla Firefox, Firefox ESR und Thunderbird: Mehrere Schwachstellen

Entryinfo

Created: 02/24/2026 16:03
Updated: 03/03/2026 13:50
Changes: 02/24/2026 16:03 (56), 02/25/2026 08:14 (2), 02/28/2026 10:33 (21), 03/02/2026 11:38 (7), 03/03/2026 13:50 (1)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

Discussion

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