Possible DoS attack using a special crafted URL in email body

published 2021-06-14 5y ago modified 2026-06-17 4mo ago also EUVD-2021-8713

cvss: 6.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.9%; EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits: 0; none known

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.

Patch / fix

fixed in 1 distros 1

otrs otrs 7.0.27, 8.0.14

otrs2 Debian 11 6.0.32-5

debian advisories DEBIAN-CVE-2021-21439

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Exploit prediction

0.88% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD	2.0	4.3	AV:N/AC:M/Au:N/C:N/I:N/A:P

Affected products

OTRS AG ((OTRS)) Community Edition
OTRS AG OTRS

Classification

Weakness

CWE-754 Improper Check for Unusual or Exceptional Conditions
CWE-755 Improper Handling of Exceptional Conditions

References

otrs.com /release-notes/otrs-security-advisory-2021-09/
vendor-advisory
lists.debian.org /debian-lts-announce/2023/08/msg00040.html
mailing-list

Sources

CVE List CVE-2021-21439
NVD CVE-2021-21439

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