What’s Vulnerable › Vulnerabilities
CVE-2021-34586: CODESYS V2 web server: crafted requests could trigger a null pointer dereference (DoS)
- Severity: high (CVSS 7.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 13.7% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2021-10-26 · updated 2026-06-17
- Weakness: CWE-476
Description
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.
Affected products
- CODESYS: before 1.1.9.22 — fixed in 1.1.9.22
- WAGO 750-8202 Firmware: before fw20 — fixed in fw20
- WAGO 750-8203 Firmware: before fw20 — fixed in fw20
- WAGO 750-8204 Firmware: before fw20 — fixed in fw20
- WAGO 750-8206 Firmware: before fw20 — fixed in fw20
- WAGO 750-8207 Firmware: before fw20 — fixed in fw20
- WAGO 750-8208 Firmware: before fw20 — fixed in fw20
- WAGO 750-8210 Firmware: before fw20 — fixed in fw20
- WAGO 750-8211 Firmware: before fw20 — fixed in fw20
- WAGO 750-8212 Firmware: before fw20 — fixed in fw20
- WAGO 750-8213 Firmware: before fw20 — fixed in fw20
- WAGO 750-8214 Firmware: before fw20 — fixed in fw20
- WAGO 750-8216 Firmware: before fw20 — fixed in fw20
- WAGO 750-8217 Firmware: before fw20 — fixed in fw20
- WAGO 750-823 Firmware: before fw10 — fixed in fw10
- WAGO 750-829 Firmware: before fw17 — fixed in fw17
- WAGO 750-831 Firmware: before fw17 — fixed in fw17
- WAGO 750-832 Firmware: before fw10 — fixed in fw10
- WAGO 750-852 Firmware: before fw17 — fixed in fw17
- WAGO 750-862 Firmware: before fw10 — fixed in fw10
- WAGO 750-880 Firmware: before fw17 — fixed in fw17
- WAGO 750-881 Firmware: before fw17 — fixed in fw17
- WAGO 750-882 Firmware: before fw17 — fixed in fw17
- WAGO 750-885 Firmware: before fw17 — fixed in fw17
- WAGO 750-889 Firmware: before fw17 — fixed in fw17
- WAGO 750-890 Firmware: before fw10 — fixed in fw10
- WAGO 750-891 Firmware: before fw10 — fixed in fw10
- WAGO 750-893 Firmware: before fw10 — fixed in fw10
How to fix
Upgrade to a fixed version: CODESYS 1.1.9.22; WAGO 750-8202 Firmware fw20; WAGO 750-8203 Firmware fw20; WAGO 750-8204 Firmware fw20; WAGO 750-8206 Firmware fw20; WAGO 750-8207 Firmware fw20; WAGO 750-8208 Firmware fw20; WAGO 750-8210 Firmware fw20; WAGO 750-8211 Firmware fw20; WAGO 750-8212 Firmware fw20; WAGO 750-8213 Firmware fw20; WAGO 750-8214 Firmware fw20. Check the vendor advisory for mitigations.
References
- https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16876&token=a3f1d937f95e7034879f4f2ea8e5a99b168256a7&download=
- https://www.tenable.com/security/research/tra-2021-47
- https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16876&token=a3f1d937f95e7034879f4f2ea8e5a99b168256a7&download=
- https://www.tenable.com/security/research/tra-2021-47
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