CVE-2021-34586

HIGHNVD 7.57.5—

7.5

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.

CVSS v3: 7.5
EG Score: 7.5(medium)
EPSS: 64.5%
KEV: Not listed

Published

October 26, 2021

Last Modified

August 15, 2025

References (4)

info@certhttps://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16876&token=a3f1d937f95e7034879f4f2ea8e5a99b168256a7&download=
info@certhttps://www.tenable.com/security/research/tra-2021-47
af854a3a-2127-422b-91ae-364da2661108https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16876&token=a3f1d937f95e7034879f4f2ea8e5a99b168256a7&download=
af854a3a-2127-422b-91ae-364da2661108https://www.tenable.com/security/research/tra-2021-47

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-476NULL Pointer Dereference

Data Freshness Timeline

(refreshed 12× in last 7d / 20× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-06-04 13:10 UTCepss_batch
2026-06-04 13:10 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 08:27 UTCEG score recompute
2026-05-26 08:27 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2021-34586?

CVE-2021-34586 is a high vulnerability published on October 26, 2021. 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.

When was CVE-2021-34586 disclosed?

CVE-2021-34586 was first published in the National Vulnerability Database on October 26, 2021, with the most recent update on August 15, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-34586 actively exploited?

CVE-2021-34586 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 64.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-34586?

CVE-2021-34586 has a CVSS v3 base score of 7.5 (NVD).

How do I remediate CVE-2021-34586?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-34586, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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CVE-2021-34586

📅 Published

🔄 Last Modified

🔗 References (4)

Weakness Classification(1)

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-34586?

🔗 Related CVEs(same CWE)

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Published

Last Modified

References (4)

Frequently asked(5)

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