Is CVE-2021-21439 actively exploited?

No active exploitation of CVE-2021-21439 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-21439 be exploited remotely?

Yes. CVE-2021-21439 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-21439?

CVE-2021-21439 has a CVSS score of 6.5 (MEDIUM).

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MEDIUM

CVE-2021-21439

CWE-754Published: June 14, 2021· Updated: Jun 17, 2026

6.5

CVSS v3.1

Official Description

DoS attack can be performed when an email contains specially designed URL in the body. It can lead to the high CPU usage and cause low quality of service, or in extreme case bring the system to a halt. This issue affects: OTRS AG ((OTRS)) Community Edition 6.0.x version 6.0.1 and later versions. OTRS AG OTRS 7.0.x version 7.0.26 and prior versions; 8.0.x version 8.0.13 and prior versions.

NVD Source

Technical Analysis

CVE-2021-21439 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 6.5.