How severe is CVE-2021-34585?

CVE-2021-34585 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-34585 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34585?

CVE-2021-34585 primarily affects Codesys. In total, 28 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-34585?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-34585 published?

CVE-2021-34585 was published on 2021-10-26 and last updated on 2026-06-17.

CVE-2021-34585

CVE-2021-34585 is a high-severity vulnerability in Codesys with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-252.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (55th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-252
Affected product: Codesys
Published: 2021-10-26
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-34585?: 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.
How severe is CVE-2021-34585?: CVE-2021-34585 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-34585 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34585?: CVE-2021-34585 primarily affects Codesys. In total, 28 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-34585?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-34585 published?: CVE-2021-34585 was published on 2021-10-26 and last updated on 2026-06-17.

References

Affected products (28)

cpe:2.3:o:wago:750-823_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-829_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-831_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-832_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-852_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-862_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-880_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-881_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-882_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-885_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-889_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-890_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-891_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-893_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8202_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8203_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8204_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8206_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8207_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8208_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8210_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8211_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8212_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8213_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8214_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8216_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8217_firmware:*:*:*:*:*:*:*:*
cpe:2.3:a:codesys:codesys:*:*:*:*:*:*:*:*

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