CVE-2021-34586
CODESYS V2 web server: crafted requests could trigger a null pointer dereference (DoS)
In the CODESYS V2 web server prior to V1.1.9.22 crafted web server requests may cause a Null pointer dereference in the CODESYS web server and may result in a denial-of-service condition.
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
CODESYS V2 web server: crafted requests could trigger a null pointer dereference (DoS)
In the CODESYS V2 web server prior to V1.1.9.22 crafted web server requests may cause a Null pointer dereference in the CODESYS web server and may result in a denial-of-service condition.
- Record
CVE-2021-34586- 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-476
- Updated
- 2026-11-02
EUVDEUVD-2021-21236
In the CODESYS V2 web server prior to V1.1.9.22 crafted web server requests may cause a Null pointer dereference in the CODESYS web server and may result in a denial-of-service condition.
- Record
EUVD-2021-21236- 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-hmwx-8xfx-mg6m
In the CODESYS V2 web server prior to V1.1.9.22 crafted web server requests may cause a Null...
In the CODESYS V2 web server prior to V1.1.9.22 crafted web server requests may cause a Null pointer dereference in the CODESYS web server and may result in a denial-of-service condition.
- Record
GHSA-hmwx-8xfx-mg6m- 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-476
- Updated
- 2026-11-02
NVD
In the CODESYS V2 web server prior to V1.1.9.22 crafted web server requests may cause a Null pointer dereference in the CODESYS web server and may result in a denial-of-service condition.
- Record
CVE-2021-34586- 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-476
- Updated
- 2026-11-02
Affected products
- codesys
- codesys v2
- wago 750-8202 firmware
- wago 750-8203 firmware
- wago 750-8204 firmware
- wago 750-8206 firmware
- wago 750-8207 firmware
- wago 750-8208 firmware
- wago 750-8210 firmware
- wago 750-8211 firmware
- wago 750-8212 firmware
- wago 750-8213 firmware
Show 17 moreShow less
- wago 750-8214 firmware
- wago 750-8216 firmware
- wago 750-8217 firmware
- wago 750-823 firmware
- wago 750-829 firmware
- wago 750-831 firmware
- wago 750-832 firmware
- wago 750-852 firmware
- wago 750-862 firmware
- wago 750-880 firmware
- wago 750-881 firmware
- wago 750-882 firmware
- wago 750-885 firmware
- wago 750-889 firmware
- wago 750-890 firmware
- wago 750-891 firmware
- wago 750-893 firmware
History
| Recorded | Changed | Sources |
|---|---|---|
| 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-2021-34586 is a high vulnerability (CVSS 7.5) in Codesys, published October 26, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 13.7%, the 96th percentile. No source names a fixed version.