How severe is CVE-2023-21687?

CVE-2023-21687 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2023-21687 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-21687?

CVE-2023-21687 primarily affects Microsoft Windows 11 21h2. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-21687?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2023-21687 published?

CVE-2023-21687 was published on 2023-02-14 and last updated on 2026-06-17.

CVE-2023-21687

CVE-2023-21687 is a medium-severity vulnerability in Microsoft Windows 11 21h2 with a CVSS 3.x base score of 5.5. 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-668.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
EPSS exploit prediction: 0% (37th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-668
Affected product: Microsoft Windows 11 21h2
Published: 2023-02-14
Last modified: 2026-06-17

Description

HTTP.sys Information Disclosure Vulnerability

Frequently asked questions

What is CVE-2023-21687?: HTTP.sys Information Disclosure Vulnerability
How severe is CVE-2023-21687?: CVE-2023-21687 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2023-21687 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-21687?: CVE-2023-21687 primarily affects Microsoft Windows 11 21h2. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-21687?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-21687 published?: CVE-2023-21687 was published on 2023-02-14 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21687

Affected products (5)

cpe:2.3:o:microsoft:windows_11_21h2:*:*:*:*:*:*:arm64:*
cpe:2.3:o:microsoft:windows_11_21h2:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_11_22h2:*:*:*:*:*:*:arm64:*
cpe:2.3:o:microsoft:windows_11_22h2:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2022:-:*:*:*:*:*:*:*

More vulnerabilities in Microsoft Windows 11 21h2

CVE-2024-38199 — Critical (CVSS 9.8): Windows Line Printer Daemon (LPD) Service Remote Code Execution Vulnerability
CVE-2024-38140 — Critical (CVSS 9.8): Windows Reliable Multicast Transport Driver (RMCAST) Remote Code Execution Vulnerability
CVE-2024-38063 — Critical (CVSS 9.8): Windows TCP/IP Remote Code Execution Vulnerability
CVE-2024-30080 — Critical (CVSS 9.8): Microsoft Message Queuing (MSMQ) Remote Code Execution Vulnerability
CVE-2023-36397 — Critical (CVSS 9.8): Windows Pragmatic General Multicast (PGM) Remote Code Execution Vulnerability
CVE-2023-36028 — Critical (CVSS 9.8): Microsoft Protected Extensible Authentication Protocol (PEAP) Remote Code Execution Vulnerability

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