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Ubuntu 26.04 LTS mailcap Critical Remote Code Execution USN-8518

Linuxsecurity •LinuxSecurity Advisories • July 8, 2026

mailcap could allow applications to escape sandbox restrictions Software Description: - mailcap: Debian's mailcap system, and support programs Details: Aaron Rainbolt discovered that the cautious-launcher utility in the mailcap package did not properly restrict the execution of certain file types. An attacker could use this issue to escape a sandboxed application and execute arbitrary code on the host operating system.

mailcap could allow applications to escape sandbox restrictions

Software Description:

- mailcap: Debian's mailcap system, and support programs

Aaron Rainbolt discovered that the cautious-launcher utility in the

mailcap package did not properly restrict the execution of certain

file types. An attacker could use this issue to escape a sandboxed

application and execute arbitrary code on the host operating system.

The problem can be corrected by updating your system to the following package versions: Ubuntu 26.04 LTS mailcap 3.75ubuntu1.1 Ubuntu 25.10 mailcap 3.74ubuntu1.1 Ubuntu 24.04 LTS mailcap 3.70+nmu1ubuntu1.24.04.1 Ubuntu 22.04 LTS mailcap 3.70+nmu1ubuntu1.22.04.1 In general, a standard system update will make all the necessary changes.

Ubuntu Security Notice USN-8518-1

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Critical mailcap Vulnerability Allows Remote Code Execution in Ubuntu A critical vulnerability in the mailcap package, discovered by Aaron Rainbolt, allows attackers to escape sandboxed applications and execute arbitrary code on the host operating system. This flaw affects multiple Ubuntu versions, including 26.04 LTS, 25.10, 24.04 LTS, and 22.04 LTS. The vulnerability arises from improper restrictions in the cautious-launcher utility. Users are advised to update their systems to mitigate this risk. The issue has been assigned the advisory USN-8518-1. A standard system update will apply the necessary changes to secure the affected systems. The vulnerability could potentially lead to significant security breaches if exploited. As of now, no active exploitation has been reported, but the severity of the flaw necessitates immediate attention. 2 sources 71

Ubuntu 26.04 LTS mailcap Critical Remote Code Execution USN-8518

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Extracted Entities

Attack Types (1)

Companies (2)