Mozilla Firefox up to 136.0.3 on Windows sandbox

Summaryinfo

A vulnerability marked as critical has been reported in Mozilla Firefox up to 136.0.3 on Windows. The impacted element is an unknown function. This manipulation causes sandbox. This vulnerability is tracked as CVE-2025-2857. The attack is possible to be carried out remotely. Moreover, an exploit is present. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Mozilla Firefox up to 136.0.3 on Windows. Affected by this vulnerability is an unknown code. The manipulation with an unknown input leads to a sandbox vulnerability. The CWE definition for the vulnerability is CWE-265. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Following the recent Chrome sandbox escape (CVE-2025-2783), various Firefox developers identified a similar pattern in our IPC code. A compromised child process could cause the parent process to return an unintentionally powerful handle, leading to a sandbox escape. The original vulnerability was being exploited in the wild. *This only affects Firefox on Windows. Other operating systems are unaffected.*. This vulnerability was fixed in Firefox 136.0.4, Firefox ESR 128.8.1, and Firefox ESR 115.21.1.

It is possible to read the advisory at bugzilla.mozilla.org. This vulnerability is known as CVE-2025-2857 since 03/27/2025. 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. Technical details are unknown but an exploit is available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 04/15/2026). The attack technique deployed by this issue is T1611 according to MITRE ATT&CK.

It is declared as proof-of-concept. The vulnerability scanner Nessus provides a plugin with the ID 233428 (Mozilla Firefox ESR < 128.8.1), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 136.0.4 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (233428). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Web Browser

Vendor

• Mozilla

Name

• Firefox

Version

• 136.0.0
• 136.0.1
• 136.0.2
• 136.0.3

License

• open-source

Website

• Vendor: https://www.mozilla.org/
• Product: https://www.mozilla.org/en-US/firefox/

CPE 2.3info

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
• 🔍

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

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

Discussion