Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2023-21687 is a medium-severity Out-of-bounds Read (CWE-125) vulnerability in Microsoft Windows 11 21H2. Its CVSS base score is 5.5 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked at the 39th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-25854
Vulnerability Data
HTTP.sys Information Disclosure Vulnerability
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Controls whether organization resources are exposed to external system spheres by permitting or prohibiting their use.
The control ensures information is not released into a security sphere where the recipient lacks matching access authorizations.
The control ensures information resources are not exposed to the incorrect (public) sphere through review and authorization.
Protects against data mining that would expose resources to unauthorized spheres by enforcing detection and controls.
Restricts information flows to ensure resources are not exposed to incorrect or unauthorized spheres.
Controlling internal connections prevents exposure of resources to unintended internal spheres.
Knowing exact processing and storage locations helps avoid exposure of resources to incorrect spheres.
The control prevents exposure of the media resource to the wrong security sphere.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Vulnerability scanning and recording can discover instances of out-of-bounds reads after code is deployed.
Routine patching replaces vulnerable code containing out-of-bounds read flaws.
Secure-development practices such as bounds checking and memory-safe languages directly prevent out-of-bounds reads.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.