CVE-2021-21439
Possible DoS attack using a special crafted URL in email body
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Possible DoS attack using a special crafted URL in email body
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.
- Record
CVE-2021-21439- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Weakness
- CWE-754
- Updated
- 2026-11-02
EUVDEUVD-2021-8713
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.
- Record
EUVD-2021-8713- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-58p7-gj75-3437
DoS attack can be performed when an email contains specially designed URL in the body. It can...
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.
- Record
GHSA-58p7-gj75-3437- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Weakness
- CWE-754, CWE-755
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2021-21439- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - CVSS 2.0
- 4.3 Medium
AV:N/AC:M/Au:N/C:N/I:N/A:P - Weakness
- CWE-754, CWE-755
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2021-21439- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVDEBIAN-CVE-2021-21439
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.
- Record
DEBIAN-CVE-2021-21439- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2021-21439
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.
- Record
UBUNTU-CVE-2021-21439- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
otrs2Debian:11 |
before 6.0.32-5, plus listed versions 2.0.4p01-102.0.4p01-112.0.4p01-122.0.4p01-132.0.4p01-14 Show 45 moreShow less2.0.4p01-14.12.0.4p01-152.0.4p01-162.0.4p01-172.0.4p01-182.0.4p01-62.0.4p01-72.0.4p01-82.0.4p01-92.0.99beta1-12.0.99beta1-22.1.1-12.1.3-12.1.4-12.1.4-22.1.5-12.1.5-22.1.5-32.1.6-12.1.7-12.1.7-22.2.0~beta2-12.2.0~beta3-12.2.1-12.2.2-12.2.3-12.2.4-12.2.5-12.2.5-22.2.6-12.2.7-12.2.7-22.2.7-2lenny12.2.7-2lenny22.2.7-2lenny32.2.7-32.3.2-12.3.2-22.3.3-12.3.4-12.3.4-22.3.4-32.3.4-42.3.4-52.3.4-6 |
6.0.32-5 |
otrs2Debian:10 From an advisory covering 32 CVEs |
before 6.0.16-2+deb10u1, plus listed versions 2.0.4p01-102.0.4p01-112.0.4p01-122.0.4p01-132.0.4p01-14 Show 45 moreShow less2.0.4p01-14.12.0.4p01-152.0.4p01-162.0.4p01-172.0.4p01-182.0.4p01-62.0.4p01-72.0.4p01-82.0.4p01-92.0.99beta1-12.0.99beta1-22.1.1-12.1.3-12.1.4-12.1.4-22.1.5-12.1.5-22.1.5-32.1.6-12.1.7-12.1.7-22.2.0~beta2-12.2.0~beta3-12.2.1-12.2.2-12.2.3-12.2.4-12.2.5-12.2.5-22.2.6-12.2.7-12.2.7-22.2.7-2lenny12.2.7-2lenny22.2.7-2lenny32.2.7-32.3.2-12.3.2-22.3.3-12.3.4-12.3.4-22.3.4-32.3.4-42.3.4-52.3.4-6 |
6.0.16-2+deb10u1 |
otrs2Ubuntu:16.04:LTS |
All versions, plus listed versions 4.0.10-15.0.1-15.0.1-25.0.2-15.0.3-15.0.5-15.0.6-15.0.7-1 |
None known |
otrs2Ubuntu:18.04:LTS |
All versions, plus listed versions 5.0.23-15.0.24-16.0.1-16.0.2-16.0.3-16.0.4-16.0.5-1 |
None known |
otrs2Ubuntu:20.04:LTS |
All versions, plus listed versions 6.0.20-16.0.23-26.0.24-16.0.25-16.0.25-26.0.25-36.0.26-1 |
None known |
otrs2Ubuntu:22.04:LTS |
All versions, plus listed versions 6.0.32-66.1.2-16.2.1-16.2.2-2 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-21439 is a medium vulnerability (CVSS 6.5) in Otrs, published June 14, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.88%, the 59th percentile. Fixed in otrs2 6.0.32-5.
References
otrs.com/release-notes/otrs-security-advisory-2021-09
lists.debian.org/debian-lts-announce/2023/08/msg00040.html
nvd.nist.gov/vuln/detail/CVE-2021-21439
github.com/advisories/GHSA-58p7-gj75-3437
security-tracker.debian.org/tracker/CVE-2021-21439
ubuntu.com/security/CVE-2021-21439
cve.org/CVERecord?id=CVE-2021-21439
Left out here: 370 versions. The JSON record has them.