Is CVE-2021-21251 actively exploited?

No active exploitation of CVE-2021-21251 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-21251 be exploited remotely?

Yes. CVE-2021-21251 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-21251?

CVE-2021-21251 has a CVSS score of 8.8 (HIGH).

HOME VULNERABILITIESCVE-2021-21251

HIGH

CVE-2021-21251

CWE-22Published: January 15, 2021· Updated: Jun 17, 2026

8.8

CVSS v3.1

Official Description

OneDev is an all-in-one devops platform. In OneDev before version 4.0.3 there is a critical "zip slip" vulnerability. This issue may lead to arbitrary file write. The KubernetesResource REST endpoint untars user controlled data from the request body using TarUtils. TarUtils is a custom library method leveraging Apache Commons Compress. During the untar process, there are no checks in place to prevent an untarred file from traversing the file system and overriding an existing file. For a successful exploitation, the attacker requires a valid __JobToken__ which may not be possible to get without using any of the other reported vulnerabilities. But this should be considered a vulnerability in `io.onedev.commons.utils.TarUtils` since it lives in a different artifact and can affect other projects using it. This issue was addressed in 4.0.3 by validating paths in tar archive to only allow them to be in specified folder when extracted.

NVD Source

Technical Analysis

CVE-2021-21251 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.8.