Security readout for executives and security teams
Plain-English summary
CVE-2025-21299 is a Windows Kerberos security feature bypass. Microsoft rates it high severity. An attacker with local low-privileged access could compromise confidentiality and integrity. This matters most on Windows servers, domain-connected endpoints, and systems where Kerberos authentication protects sensitive access.
Executive priority
Treat as a high-priority Windows patching item, especially for enterprise authentication environments. There is no provided evidence of active exploitation, but the confidentiality and integrity impacts justify prompt remediation through normal emergency or accelerated patch processes.
Technical view
The CVSS 3.1 score is 7.1 with local attack vector, low complexity, low privileges, no user interaction, and high confidentiality and integrity impact. Microsoft identifies the issue as CWE-922. A Microsoft fix is listed, but the provided sources do not include deeper root-cause details.
Likely exposure
Exposure includes listed Windows 10, Windows 11, Windows Server 2016, 2019, 2022, and 2025 versions, including Server Core variants. Organizations with unpatched supported Windows fleets should assume potential exposure until patch status is verified.
Exploitation context
The provided data does not show CISA KEV listing or cited active exploitation. CVSS indicates exploitation requires local access and low privileges, with no user interaction. Microsoft’s exploit maturity field is unproven in the provided CVSS vector.
Researcher notes
Public details in the provided sources are limited to Microsoft and CVE metadata. Do not infer exploit mechanics beyond the CVSS characteristics. Useful research focus is patch diffing, affected build confirmation, and enterprise detection opportunities without publishing weaponizable details.
Mitigation direction
- Apply Microsoft’s security update for CVE-2025-21299 or current cumulative updates.
- Prioritize Windows servers, domain-connected systems, and shared workstations.
- Review Microsoft guidance for any version-specific installation requirements.
- Retire or isolate Windows versions that cannot receive updates.
Validation and detection
- Inventory affected Windows client and server versions listed by Microsoft.
- Confirm the relevant Microsoft update is installed on each system.
- Check patch coverage for Server Core installations separately.
- Track exceptions and compensating controls for unpatched systems.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-922: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2025-21299 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C1.85.2microsoftVulnerability scoring details
Base CVSS 3.1 score
7.1HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- Windows Kerberos Security Feature Bypass VulnerabilityCVE reference, microsoft · vendor-advisory, patch
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Insecure Storage of Sensitive Information
Insecure Storage of Sensitive Information represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.