Mozilla Thunderbird MessagePort use after free

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.3	$5k-$25k	0.00

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Mozilla Thunderbird. This vulnerability affects unknown code of the component MessagePort Handler. The manipulation leads to use after free. This vulnerability is uniquely identified as CVE-2023-6205. The attack is possible to be carried out remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Mozilla Thunderbird (Mail Client Software) (affected version unknown). It has been rated as problematic. This issue affects an unknown functionality of the component MessagePort Handler. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is availability. The summary by CVE is:

It was possible to cause the use of a MessagePort after it had already been freed, which could potentially have led to an exploitable crash. This vulnerability affects Firefox < 120, Firefox < 115.5, and Thunderbird < 115.5.0.

The weakness was disclosed 11/21/2023. The advisory is shared at bugzilla.mozilla.org. The identification of this vulnerability is CVE-2023-6205 since 11/20/2023. 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 06/19/2025).

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

🔍

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.4
VulDB Meta Temp Score: 5.3

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 6.5
NVD Vector: 🔍

CVSSv2info

AV	AC	Au	C	I	A
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💳	💳	💳	💳	💳	💳
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 239860
Nessus Name: TencentOS Server 2: firefox (TSSA-2023:0316)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Timelineinfo

11/20/2023 🔍
11/21/2023 +1 days 🔍
11/21/2023 +0 days 🔍
06/19/2025 +576 days 🔍

Sourcesinfo

Vendor: mozilla.org

Advisory: DLA 3661-1
Status: Confirmed

CVE: CVE-2023-6205 (🔍)
GCVE (CVE): GCVE-0-2023-6205
GCVE (VulDB): GCVE-100-245897

Entryinfo

Created: 11/21/2023 16:12
Updated: 06/19/2025 14:53
Changes: 11/21/2023 16:12 (38), 12/15/2023 09:39 (1), 12/15/2023 09:40 (11), 06/19/2025 14:53 (17)
Complete: 🔍
Cache ID: 216::103

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