CVE-2021-21439

Possible DoS attack using a special crafted URL in email body

MEDIUM
6.5
CVSS Score
Published: June 14, 2021 at 07:55 AM UTC
Updated: June 17, 2026 at 03:35 AM UTC
1 product affected across 1 vendorOTRS

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.9%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

6.0.1 ≤ v ≤ 6.0.306.0.1 ≤ v < 6.0.x*7.0.0 ≤ v < 7.0.277.0.x ≤ v ≤ 7.0.268.0.0 ≤ v < 8.0.148.0.x ≤ v ≤ 8.0.136.0.17.0.x8.0.x
Affected range stops below 6.0.x*, so it looks safe — our inference, not a vendor statement
Affected range stops below 7.0.27, so it looks safe — our inference, not a vendor statement
Affected range stops below 8.0.14, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

6.5MEDIUMOTRS
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-754CWE-755

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