CVE-2021-31955
Microsoft Windows 10 1809 ≤ 10.0.17763.1999
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:NSummary
CVE-2021-31955 is a medium-severity Exposure of Sensitive System Information to an Unauthorized Control Sphere (CWE-497) vulnerability in Microsoft Windows 10 1809. Its CVSS base score is 5.5 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique System Information Discovery (T1082); ranked in the top 0.4% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2021-31955 is a Windows Kernel information disclosure vulnerability, assigned CWE-497, with a CVSS 3.1 base score of 5.5 reflecting local attack vector, low complexity, and low privileges required. It affects the Windows kernel component and permits exposure of sensitive information without requiring user interaction.
A local attacker with low privileges can exploit the flaw to read kernel memory contents, achieving high confidentiality impact while leaving integrity and availability unaffected. The vulnerability can be triggered through standard local execution paths on affected Windows systems.
Microsoft has published security guidance addressing the issue via its advisory portal, and the vulnerability appears in CISA's catalog of known exploited vulnerabilities, confirming observed real-world exploitation activity.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-18828
Vulnerability Data
Windows Kernel Information Disclosure Vulnerability
- CWE(s)
- KEV Date Added
- 03 November 2021
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 5 hardening rules · 4 OS baselines
V14.1.2
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.
Ongoing reviews detect and remove sensitive system information before it reaches publicly accessible systems.
Employs detection to prevent unauthorized mining of sensitive system information from being exfiltrated to external control spheres.
Documenting where system information is processed and stored prevents exposure to unauthorized control spheres.
The control stops sensitive system information from crossing into unauthorized control spheres through EM emanations.
Authorization and minimization requirements keep PII out of test/research control spheres that often lack production-grade protections.
Documented categorization of system information reduces the chance that sensitive internals are left exposed to unauthorized spheres.
System information is concealed or replaced with decoys, reducing leakage to unauthorized observers.
Ensures sensitive system information is not disclosed outside the intended control sphere through error output.
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.
Enforcing least-privilege access permissions directly prevents unauthorized actors from reaching sensitive system information.
Protecting environments from unauthorized logical access stops exposure of internal system details to outsiders.
Secure-development practices reduce the chance of code paths that leak sensitive system information.
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.
Keeping internal maps, directories, and signage from public view prevents disclosure of system or facility details that could aid reconnaissance or targeted attacks.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (2 rules)
- V-248551 A sticky bit must be set on all OL 8 public directories to prevent unauthorized and unintended information transferred via shared system resources. prevents CWE-497
- V-248580 OL 8 must prevent kernel profiling by unprivileged users. prevents CWE-497
RHEL 8 (1 rule)
- V-230270 RHEL 8 must prevent kernel profiling by unprivileged users. prevents CWE-497
Ubuntu 22.04 (1 rule)
- V-260470 Ubuntu 22.04 LTS, when booted, must require authentication upon booting into single-user and maintenance modes. prevents CWE-497
Ubuntu 24.04 (1 rule)
- V-270675 Ubuntu 24.04 LTS when booted must require authentication upon booting into single-user and maintenance modes. prevents CWE-497