Mozilla Firefox up to 128.6/134.x JavaScript Engine use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.8$5k-$25k0.00

Summaryinfo

A vulnerability identified as critical has been detected in Mozilla Firefox up to 128.6/134.x. Affected by this issue is some unknown functionality of the component JavaScript Engine. This manipulation causes use after free. This vulnerability is registered as CVE-2025-1012. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Mozilla Firefox up to 128.6/134.x. Affected by this vulnerability is some unknown functionality 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:

A race during concurrent delazification could have led to a use-after-free. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.

The advisory is shared at bugzilla.mozilla.org. This vulnerability is known as CVE-2025-1012 since 02/04/2025. 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 10/05/2026).

The vulnerability scanner Nessus provides a plugin with the ID 214959 (Mozilla Firefox ESR < 115.20), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 128.7 or 135 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (214959). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.9
VulDB Meta Temp Score: 7.8

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

NVD Base Score: 7.5
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: 🔍

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Nessus ID: 214959
Nessus Name: Mozilla Firefox ESR < 115.20

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Firefox 128.7/135

Timelineinfo

02/04/2025 🔍
02/04/2025 +0 days 🔍
02/04/2025 +0 days 🔍
10/05/2026 +608 days 🔍

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2025-1012 (🔍)
GCVE (CVE): GCVE-0-2025-1012
GCVE (VulDB): GCVE-100-294625

Entryinfo

Created: 02/04/2025 15:44
Updated: 10/05/2026 18:51
Changes: 02/04/2025 15:44 (23), 02/04/2025 15:47 (33), 02/04/2025 22:11 (2), 02/05/2025 22:17 (3), 04/15/2026 08:30 (22), 09/30/2026 22:43 (3), 10/05/2026 18:51 (1)
Complete: 🔍
Committer: mitr
Cache ID: 216::103

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

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