Incus vulnerable to local privilege escalation through VM screenshot path

Incus is a system container and virtual machine manager. Incus provides an API to retrieve VM screenshots. That API relies on the use of a temporary file for QEMU to write the screenshot to which is then picked up and sent to the user prior to deletion. As versions prior to 6.23.0 use predictable paths under /tmp for this, an attacker with local access to the system can abuse this mechanism by creating their own symlinks ahead of time. On the vast majority of Linux systems, this will result in a "Permission denied" error when requesting a screenshot. That's because the Linux kernel has a security feature designed to block such attacks, `protected_symlinks`. On the rare systems with this purposefully disabled, it's then possible to trick Incus intro truncating and altering the mode and permissions of arbitrary files on the filesystem, leading to a potential denial of service or possible local privilege escalation. Version 6.23.0 fixes the issue.

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CWE-61

Incus 安全漏洞

Incus是LXC开源的一个系统容器和虚拟机管理器。 Incus 6.23.0之前版本存在安全漏洞，该漏洞源于使用可预测的临时文件路径，可能导致拒绝服务或本地权限提升。

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