CVE-2026-33825
Microsoft Defender Antimalware Platform ≤ 4.18.26030.3011
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2026-33825 is a high-severity Insufficient Granularity of Access Control (CWE-1220) vulnerability in Microsoft Defender Antimalware Platform. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Services File Permissions Weakness (T1574.010); ranked in the top 7% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.
The strongest mitigations our analysis identified map to AC-24 (Access Control Decisions) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
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-2026-33825 is an insufficient-granularity access-control flaw in Microsoft Defender that permits local privilege escalation. The vulnerability carries a CVSS 3.1 base score of 7.8 and is tracked under CWE-1220; it affects the Microsoft Defender component running on supported Windows platforms.
An attacker who already possesses a local, low-privileged account can exploit the weakness without user interaction to obtain higher privileges on the affected system. The attack vector is strictly local (AV:L) and requires only low attack complexity once code execution is achieved under the initial account.
Microsoft’s advisory at msrc.microsoft.com details the affected builds and supplies the corresponding security update; CISA has added the CVE to its Known Exploited Vulnerabilities catalog, confirming active in-the-wild use. The Huntress report “Nightmare Eclipse Intrusion” further documents observed post-exploitation activity tied to this issue.
EPSS for the vulnerability rose from a low baseline to a peak of 0.1376 nine days after disclosure on 14 April 2026 before receding to its current value of 0.0789, indicating a transient but measurable increase in exploitation interest following public release.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-22643
Vulnerability Data
Insufficient granularity of access control in Microsoft Defender allows an authorized attacker to elevate privileges locally.
- CWE(s)
- KEV Date Added
- 22 April 2026
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 4 hardening rules · 4 OS baselines
V16.4.2V8.4.2V11.7.1V13.2.4
Mitigating Controls (NIST 800-53 r5) AI
Least privilege explicitly demands that only the minimum necessary accesses are granted, eliminating the broad permissions that define this weakness.
AC-24 requires access decisions to be applied precisely and unambiguously to every request, structurally blocking insufficiently granular policies.
AC-3 requires enforcement of authorizations according to policy, directly compelling sufficiently granular rules so broad allowances cannot be introduced.
AC-4 enforces approved information flows with explicit source/destination rules, preventing overly coarse access policies from being deployed.
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.
PR.IR-01's segmentation + zero-trust rules directly enforce minimum-necessary access at network boundaries, removing most instances of overly broad policy; CWE-1220 can still exist in application-layer or intra-segment controls that this single outcome does not address.
PR.PS-06's general SDLC practices can surface granularity issues during design/review (partial prevention) but do not specifically target access-control policy breadth, so they remove only part of CWE-1220's risk.
CWE-1220 permits unauthorized access to sensitive assets but neither prevents nor impairs the delivery of adverse-event information to authorized recipients.
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.
Directly requires information-access restriction at the level of individual assets and operations, addressing the granularity gap.
Establishes the overarching access-control policy whose granularity directly determines whether the weakness exists.
Defines the assignment and review of access rights; insufficient granularity in those rights is the root of CWE-1220.
Specifies management of privileged access rights, where overly broad privileges are a common manifestation of the weakness.
Limits use of privileged utilities; overly coarse access rules can still allow unauthorized utility access.
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).
Windows Server 2016 (1 rule)
- V-225025 Local accounts with blank passwords must be restricted to prevent access from the network. prevents CWE-1220
Windows Server 2022 (1 rule)
- V-254446 Windows Server 2022 must prevent local accounts with blank passwords from being used from the network. prevents CWE-1220