How severe is CVE-2025-21343?

CVE-2025-21343 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 high, integrity none, and availability none.

Is CVE-2025-21343 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-21343?

CVE-2025-21343 primarily affects Microsoft Windows 11 22h2. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-21343?

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-2025-21343 have an EU (EUVD) identifier?

Yes. CVE-2025-21343 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-2408.

When was CVE-2025-21343 published?

CVE-2025-21343 was published on 2025-01-14 and last updated on 2026-06-17.

CVE-2025-21343

CVE-2025-21343 is a high-severity vulnerability in Microsoft Windows 11 22h2 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-269.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (67th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-2408
Weakness: CWE-269
Affected product: Microsoft Windows 11 22h2
Published: 2025-01-14
Last modified: 2026-06-17

Description

Windows Web Threat Defense User Service Information Disclosure Vulnerability

Frequently asked questions

What is CVE-2025-21343?: Windows Web Threat Defense User Service Information Disclosure Vulnerability
How severe is CVE-2025-21343?: CVE-2025-21343 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 high, integrity none, and availability none.
Is CVE-2025-21343 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-21343?: CVE-2025-21343 primarily affects Microsoft Windows 11 22h2. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-21343?: 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-2025-21343 have an EU (EUVD) identifier?: Yes. CVE-2025-21343 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-2408.
When was CVE-2025-21343 published?: CVE-2025-21343 was published on 2025-01-14 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21343

Affected products (3)

cpe:2.3:o:microsoft:windows_11_22h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:*:*

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