#VU79751 Path traversal in Docker - CVE-2020-27534

Vulnerability identifier: #VU79751

Vulnerability risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-27534

CWE-ID: CWE-22

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Docker
Server applications / Virtualization software

Vendor: Docker Inc.

Description

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

The vulnerability exists due to util/binfmt_misc/check.go calls os.OpenFile with a potentially unsafe qemu-check temporary pathname, constructed with an empty first argument in an ioutil.TempDir call. A remote attacker can send a specially crafted HTTP request and read arbitrary files on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Docker: 19.03.0 - 19.03.8

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External links
https://web.archive.org/web/20200530054359/
https://docs.docker.com/engine/release-notes/
https://github.com/moby/buildkit/pull/1462
https://github.com/moby/moby/pull/40877
https://golang.org/pkg/io/ioutil/#TempDir
https://golang.org/pkg/os/#TempDir

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.