#VU49272 Path traversal in Flink - CVE-2020-17518

Vulnerability identifier: #VU49272

Vulnerability risk: Medium

CVSSv4.0: 7.4 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2020-17518

CWE-ID: CWE-22

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Flink
Server applications / Database software

Vendor: Apache Foundation

Description

The vulnerability allows a remote user to perform directory traversal attacks.

The vulnerability exists due to input validation error when processing directory traversal sequences while uploading files via a REST handler. A remote user can send a specially crafted HTTP request with a modified HTTP header and upload files to an arbitrary location on the system.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Flink: 1.5.1 - 1.11.2

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External links
https://lists.apache.org/thread.html/rb43cd476419a48be89c1339b527a18116f23eec5b6df2b2acbfef261%40%3Cdev.flink.apache.org%3E

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.