How severe is CVE-2026-21218?

CVE-2026-21218 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 high, and availability none.

Is CVE-2026-21218 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21218?

CVE-2026-21218 affects Microsoft .net. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-21218?

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.

Does CVE-2026-21218 have an EU (EUVD) identifier?

Yes. CVE-2026-21218 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-7347.

When was CVE-2026-21218 published?

CVE-2026-21218 was published on 2026-02-10 and last updated on 2026-06-17.

CVE-2026-21218

CVE-2026-21218 is a high-severity vulnerability in Microsoft .net 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-166.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-7347
Weakness: CWE-166
Affected product: Microsoft .net
Published: 2026-02-10
Last modified: 2026-06-17

Description

Improper handling of missing special element in .NET allows an unauthorized attacker to perform spoofing over a network.

Frequently asked questions

What is CVE-2026-21218?: Improper handling of missing special element in .NET allows an unauthorized attacker to perform spoofing over a network.
How severe is CVE-2026-21218?: CVE-2026-21218 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 high, and availability none.
Is CVE-2026-21218 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21218?: CVE-2026-21218 affects Microsoft .net. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-21218?: 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.
Does CVE-2026-21218 have an EU (EUVD) identifier?: Yes. CVE-2026-21218 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-7347.
When was CVE-2026-21218 published?: CVE-2026-21218 was published on 2026-02-10 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21218

Affected products (1)

cpe:2.3:a:microsoft:.net:*:*:*:*:*:*:*:*

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