Mozilla Thunderbird up to 136 URL ui layer

Summaryinfo

A vulnerability has been found in Mozilla Thunderbird up to 136 and classified as problematic. Affected is an unknown function of the component URL Handler. Performing a manipulation results in ui layer. This vulnerability is reported as CVE-2025-3029. The attack is possible to be carried out remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as problematic has been found in Mozilla Thunderbird up to 136. This affects an unknown part of the component URL Handler. The manipulation with an unknown input leads to a ui layer vulnerability. CWE is classifying the issue as CWE-1021. The web application does not restrict or incorrectly restricts frame objects or UI layers that belong to another application or domain, which can lead to user confusion about which interface the user is interacting with. This is going to have an impact on integrity. The summary by CVE is:

A crafted URL containing specific Unicode characters could have hidden the true origin of the page, resulting in a potential spoofing attack. This vulnerability was fixed in Firefox 137, Firefox ESR 128.9, Thunderbird 137, and Thunderbird 128.9.

The advisory is shared at bugzilla.mozilla.org. This vulnerability is uniquely identified as CVE-2025-3029 since 03/31/2025. The exploitability is told to be easy. 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. 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 04/15/2026).

The vulnerability scanner Nessus provides a plugin with the ID 233651 (Mozilla Firefox ESR < 128.9), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 137 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (233651). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Mail Client Software

Vendor

• Mozilla

Name

• Thunderbird

Version

• 136

License

• open-source

Website

• Vendor: https://www.mozilla.org/

CPE 2.3info

• 🔍

CPE 2.2info

• 🔍

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

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

Discussion