CVE-2021-21002
Denial of Service in Phoenix Contact FL COMSERVER UNI products
In Phoenix Contact FL COMSERVER UNI in versions < 2.40 a invalid Modbus exception response can lead to a temporary denial of service.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Denial of Service in Phoenix Contact FL COMSERVER UNI products
In Phoenix Contact FL COMSERVER UNI in versions < 2.40 a invalid Modbus exception response can lead to a temporary denial of service.
- Record
CVE-2021-21002- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-772
- Updated
- 2026-11-02
EUVDEUVD-2021-8411
In Phoenix Contact FL COMSERVER UNI in versions < 2.40 a invalid Modbus exception response can lead to a temporary denial of service.
- Record
EUVD-2021-8411- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-wc86-7c83-q7g5 No score
In Phoenix Contact FL COMSERVER UNI in versions < 2.40 a invalid Modbus exception response can...
In Phoenix Contact FL COMSERVER UNI in versions < 2.40 a invalid Modbus exception response can lead to a temporary denial of service.
- Record
GHSA-wc86-7c83-q7g5- Weakness
- CWE-772
- Updated
- 2026-11-02
NVD
In Phoenix Contact FL COMSERVER UNI in versions < 2.40 a invalid Modbus exception response can lead to a temporary denial of service.
- Record
CVE-2021-21002- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:N/A:P - Weakness
- CWE-772
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| facts | ||
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-21002 is a high vulnerability (CVSS 7.5) in Phoenix Contact Fl Comserver, published June 25, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.96%, the 61st percentile. No source names a fixed version.