Mozilla Thunderbird Relative URL path traversal

Summaryinfo

A vulnerability was found in Mozilla Thunderbird. It has been rated as critical. This impacts an unknown function of the component Relative URL Handler. The manipulation leads to path traversal. This vulnerability is listed as CVE-2023-6209. The attack may be initiated remotely. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Mozilla Thunderbird (Mail Client Software) (version unknown) and classified as critical. This issue affects an unknown function of the component Relative URL Handler. The manipulation with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Relative URLs starting with three slashes were incorrectly parsed, and a path-traversal "/../" part in the path could be used to override the specified host. This could contribute to security problems in web sites. This vulnerability affects Firefox < 120, Firefox < 115.5, and Thunderbird < 115.5.0.

The weakness was presented 11/21/2023. It is possible to read the advisory at bugzilla.mozilla.org. The identification of this vulnerability is CVE-2023-6209 since 11/20/2023. 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 06/19/2025). The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 239860 (TencentOS Server 2: firefox (TSSA-2023:0316)), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (239860). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• Mail Client Software

Vendor

• Mozilla

Name

• Thunderbird

License

• open-source

Website

• Vendor: https://www.mozilla.org/

CPE 2.3info

• 🔍

CPE 2.2info

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Entryinfo

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