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CVE-2021-34585

CODESYS V2 web server: crafted requests could trigger a pointer dereference with an invalid address (DoS)

HIGH

7.5

CVSS Score

Published: October 26, 2021 at 09:55 AM UTC

Updated: June 17, 2026 at 03:56 AM UTC

55 products affected across 2 vendors750-8202 Firmware750-862 Firmware750-823 Firmware

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Severity

HIGH7.5

Exploit prediction

EPSS 0.9%

Description

In the CODESYS V2 web server prior to V1.1.9.22 crafted web server requests can trigger a parser error. Since the parser result is not checked under all conditions, a pointer dereference with an invalid address can occur. This leads to a denial of service situation.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

CODESYS · Codesys

95%

v < 1.1.9.22all web servers ≤ v < V1.1.9.22all web servers

Affected range stops below 1.1.9.22, so it looks safe — our inference, not a vendor statement

Affected range stops below V1.1.9.22, so it looks safe — our inference, not a vendor statement

750-8202 Firmware · WAGO

95%

v < fw20

Affected range stops below fw20, so it looks safe — our inference, not a vendor statement

wago-750-8202 (same device)

750-8203 Firmware · WAGO

95%

v < fw20

Affected range stops below fw20, so it looks safe — our inference, not a vendor statement

wago-750-8203 (same device)

750-8204 Firmware · WAGO

95%

v < fw20

Affected range stops below fw20, so it looks safe — our inference, not a vendor statement

wago-750-8204 (same device)

750-8206 Firmware · WAGO

95%

v < fw20

Affected range stops below fw20, so it looks safe — our inference, not a vendor statement

wago-750-8206 (same device)

750-8207 Firmware · WAGO

95%

v < fw20

Affected range stops below fw20, so it looks safe — our inference, not a vendor statement

wago-750-8207 (same device)

750-8208 Firmware · WAGO

95%

v < fw20

Affected range stops below fw20, so it looks safe — our inference, not a vendor statement

wago-750-8208 (same device)

750-8210 Firmware · WAGO

95%

v < fw20

Affected range stops below fw20, so it looks safe — our inference, not a vendor statement

wago-750-8210 (same device)

750-8211 Firmware · WAGO

95%

v < fw20

Affected range stops below fw20, so it looks safe — our inference, not a vendor statement

wago-750-8211 (same device)

750-8212 Firmware · WAGO

95%

v < fw20

Affected range stops below fw20, so it looks safe — our inference, not a vendor statement

wago-750-8212 (same device)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16876&token=a3f1d937f95e7034879f4f2ea8e5a99b168256a7&download=

References (2)

x_refsource_CONFIRMVendor Advisory

Source: [email protected]

https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16876&token=a3f1d937f95e7034879f4f2ea8e5a99b168256a7&download=

x_refsource_MISCExploitThird Party Advisory

Source: [email protected]

https://www.tenable.com/security/research/tra-2021-47

CVSS

7.5HIGHCERTVDE

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusANALYZED

CWE

CWE-252

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