Mozilla Firefox up to 70.x Soft Token Session use after free

Summaryinfo

A vulnerability was found in Mozilla Firefox up to 70.x. It has been classified as critical. The impacted element is an unknown function of the component Soft Token Session Handler. Performing a manipulation results in use after free. This vulnerability is cataloged as CVE-2019-11756. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical has been found in Mozilla Firefox up to 70.x (Web Browser). This affects an unknown code block of the component Soft Token Session Handler. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Improper refcounting of soft token session objects could cause a use-after-free and crash (likely limited to a denial of service). This vulnerability affects Firefox < 71.

The weakness was shared 01/08/2020 as Bug 1508776 as not defined bug report (Bugzilla). It is possible to read the advisory at bugzilla.mozilla.org. This vulnerability is uniquely identified as CVE-2019-11756 since 05/03/2019. It is possible to initiate the attack remotely. No form of authentication is needed for 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 $0-$5k at the moment (estimation calculated on 08/16/2025).

The vulnerability scanner Nessus provides a plugin with the ID 250248 (Linux Distros Unpatched Vulnerability : CVE-2019-11756), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 71.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (250248). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Web Browser

Vendor

• Mozilla

Name

• Firefox

Version

• 70.x

License

• open-source

Website

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

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

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