CVE-2025-21204
Microsoft Windows Server 2008 r2
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2025-21204 is a high-severity Link Following (CWE-59) vulnerability in Microsoft Windows Server 2008. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception (T1034); ranked in the top 6% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-6 (Least Privilege) — 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-2025-21204 is an improper link resolution before file access vulnerability, also described as a link-following issue, that affects the Windows Update Stack. The flaw carries a CVSS 3.1 base score of 7.8 and is tracked under CWE-59; successful exploitation permits an attacker to perform unauthorized file operations that lead to privilege escalation on the local system.
An authorized local attacker with low privileges can exploit the weakness without user interaction. By supplying a crafted link that the update stack resolves incorrectly, the attacker can read, write, or modify protected files, resulting in full control over confidentiality, integrity, and availability on the affected host.
Microsoft’s Security Response Center advisory at msrc.microsoft.com provides official guidance, while independent resources from Vicarius supply PowerShell-based detection and mitigation scripts that practitioners can use to identify unpatched systems and apply workarounds until updates are installed.
EPSS for the CVE rose from lower values to a recorded peak of 0.0733 on 2026-02-03 before receding to the current 0.0481, indicating a measurable post-disclosure increase in exploitation interest that later subsided.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-10245
Vulnerability Data
Improper link resolution before file access ('link following') in Windows Update Stack allows an authorized attacker to elevate privileges locally.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V15.4.2
Mitigating Controls (NIST 800-53 r5) AI
Proper enforcement of access authorizations on the resolved target resource stops a link from reaching an unintended object.
Least-privilege limits the damage an attacker can cause after following an unintended link.
Validating file-name inputs can reject or canonicalize names that resolve to links before access occurs.
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.
Secure SDLC practices directly require code to validate paths and avoid unsafe link following.
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.
Security testing can detect link-following flaws before release.
Secure SDLC practices can mandate link-resolution checks and canonicalization before file access.
Application security requirements can explicitly require safe handling of symbolic links and path traversal.
Secure architecture principles include input validation and safe file-access design patterns.
Secure coding standards directly address canonicalization and symlink attacks during implementation.
Access-control rules can limit which files are reachable, reducing exposure to malicious links.