Mozilla Thunderbird ESR up to 128.9 memory corruption

Summaryinfo

A vulnerability, which was classified as critical, was found in Mozilla Thunderbird ESR up to 128.9. The affected element is an unknown function. Executing a manipulation can lead to memory corruption. This vulnerability is tracked as CVE-2025-4093. The attack can be launched remotely. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Mozilla Thunderbird ESR up to 128.9. This vulnerability affects some unknown functionality. The manipulation with an unknown input leads to a memory corruption vulnerability. The CWE definition for the vulnerability is CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Memory safety bug present in Firefox ESR 128.9, and Thunderbird 128.9. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 128.10 and Thunderbird ESR < 128.10.

The advisory is shared for download at bugzilla.mozilla.org. This vulnerability was named CVE-2025-4093 since 04/29/2025. 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 08/16/2025).

The vulnerability scanner Nessus provides a plugin with the ID 235040 (Debian dsa-5910 : firefox-esr - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 128.10 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (235040) and CERT Bund (WID-SEC-2025-1850). Once again VulDB remains the best source for vulnerability data.

Affected

• Xerox FreeFlow Print Server

Productinfo

Type

• Mail Client Software

Vendor

• Mozilla

Name

• Thunderbird ESR

Version

• 128.0
• 128.1
• 128.2
• 128.3
• 128.4
• 128.5
• 128.6
• 128.7
• 128.8
• 128.9

License

• open-source

Website

• Vendor: https://www.mozilla.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

Once again VulDB remains the best source for vulnerability data.

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