Security Resilience

CVE-2021-34486

Memory Safety in Microsoft Windows 10 1809 ≤ 10.0.17763.2114

CISA KEVActive ExploitationEUVD ExploitedMemory Safety
Published
12 August 2021
Modified
10 August 2026
KEV Added
28 March 2022
Patch / advisory
CVSS Score v3.1 7.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.093 95th percentile
Risk Priority 83 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2021-34486 is a high-severity Use After Free (CWE-416) vulnerability in Microsoft Windows 10 1809. Its CVSS base score is 7.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique OS Credential Dumping (T1003); ranked in the top 5% 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.

Windows Event Tracing contains an elevation of privilege vulnerability tracked as CVE-2021-34486 and assigned CWE-416 for use-after-free. The flaw affects the Windows Event Tracing component and carries a CVSS 3.1 base score of 7.8 reflecting local attack vector, low complexity, low privileges required, and high impact on confidentiality, integrity, and availability.

A local attacker with low privileges can exploit the condition without user interaction to execute arbitrary code with elevated rights on the affected system. Successful exploitation grants the attacker full control over the compromised host.

Microsoft's security advisory and the CISA Known Exploited Vulnerabilities catalog both reference this issue, confirming that patches are available through standard Windows update channels and that the vulnerability has been observed in active exploitation.

EU & UK References

Vulnerability Data

Windows Event Tracing Elevation of Privilege Vulnerability

CWE(s)
KEV Date Added
28 March 2022

Related Threats

MITRE ATT&CK Enterprise Techniques

T1003 OS Credential Dumping Credential Access
Adversaries may attempt to dump credentials to obtain account login and credential material, normally in the form of a hash or a clear text password.
T1003.001 LSASS Memory Credential Access
Adversaries may attempt to access credential material stored in the process memory of the Local Security Authority Subsystem Service (LSASS).
T1003.004 LSA Secrets Credential Access
Adversaries with SYSTEM access to a host may attempt to access Local Security Authority (LSA) secrets, which can contain a variety of different credential materials, such as credentials for service accounts.
T1007 System Service Discovery Discovery
Adversaries may try to gather information about registered local system services.
T1008 Fallback Channels Command And Control
Adversaries may use fallback or alternate communication channels if the primary channel is compromised or inaccessible in order to maintain reliable command and control and to avoid data transfer thresholds.
T1011 Exfiltration Over Other Network Medium Exfiltration
Adversaries may attempt to exfiltrate data over a different network medium than the command and control channel.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2021-31166Same product: Microsoft Windows 10 2004both on KEV
CVE-2021-40449Same product: Microsoft Windows 10 1809both on KEV
CVE-2021-26411Same product: Microsoft Windows 10 1809both on KEV
CVE-2023-21674Same product: Microsoft Windows 10 1809both on KEV
CVE-2023-36802Same product: Microsoft Windows 10 1809both on KEV
CVE-2020-0674Same product: Microsoft Windows 10 1809both on KEV
CVE-2025-62221Same product: Microsoft Windows 10 1809both on KEV
CVE-2025-30400Same product: Microsoft Windows 10 1809both on KEV
CVE-2024-38107Same product: Microsoft Windows 10 1809both on KEV
CVE-2024-38193Same product: Microsoft Windows 10 1809both on KEV

Affected Assets

microsoft
windows 10 1809
≤ 10.0.17763.2114
microsoft
windows 10 1909
≤ 10.0.18363.1734
microsoft
windows 10 2004
≤ 10.0.19041.1165
microsoft
windows 10 20h2
≤ 10.0.19042.1165
microsoft
windows 10 21h1
≤ 10.0.19043.1165
microsoft
windows server 2004
≤ 10.0.19041.1165
microsoft
windows server 2019
≤ 10.0.17763.2114
microsoft
windows server 20h2
≤ 10.0.19042.1165

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 3 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V1.4.3

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.

addresses: CWE-416

Use-after-free exploits that achieve arbitrary code execution are blocked or significantly hardened by non-executable pages and ASLR.

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.

ID.RA-01 partial match
blocks

Vulnerability identification processes can discover use-after-free issues via scanning or analysis but do not prevent their introduction.

PR.PS-02 partial match
blocks

Routine patching removes known use-after-free instances after they have been introduced in released software.

PR.PS-06 partial match
blocks

Secure SDLC practices directly incorporate memory-safety tooling and reviews that prevent most use-after-free defects.

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.

removes
removes
removes
removes

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` (higher-evidence rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248592 OL 8 must clear memory when it is freed to prevent use-after-free attacks. blocks CWE-416
RHEL 8 (1 rule)
  • V-230279 RHEL 8 must clear memory when it is freed to prevent use-after-free attacks. blocks CWE-416
RHEL 9 (1 rule)
  • V-257794 RHEL 9 must clear memory when it is freed to prevent use-after-free attacks. blocks CWE-416

References