Security readout for executives and security teams
Plain-English summary
CVE-2021-1641 is a Microsoft SharePoint spoofing vulnerability. An attacker with low privileges could mislead a user and cause limited confidentiality or integrity impact. The source bundle rates it medium severity with no availability impact and no evidence of active exploitation.
Executive priority
Handle as a medium-priority SharePoint patching item. It is not shown as actively exploited in the provided evidence, but SharePoint often supports sensitive collaboration workflows, so unpatched exposed instances deserve timely remediation.
Technical view
The CVSS 3.1 vector is 4.6: network reachable, low attack complexity, low privileges required, user interaction required, unchanged scope, low confidentiality and integrity impact, no availability impact. Affected products listed are SharePoint Enterprise Server 2016, SharePoint Foundation 2013 SP1, and SharePoint Server 2019.
Likely exposure
Exposure is most likely in organizations running the listed on-premises SharePoint products, especially where user-authenticated SharePoint access is broad. Actual exposure depends on exact build, patch level, and whether the vulnerable user-interaction path exists in that deployment.
Exploitation context
The bundle does not identify CISA KEV listing, and the CVSS exploit maturity is unproven. No provided source confirms active exploitation or public weaponization. Treat exploitation status as unconfirmed based on available evidence.
Researcher notes
Evidence is limited to CVE and Microsoft metadata. Do not infer other SharePoint editions or cloud services are affected. Validation should focus on exact product, version, update status, privilege requirements, and the user-interaction condition described by the CVSS vector.
Mitigation direction
- Check Microsoft’s CVE-2021-1641 Update Guide for applicable SharePoint security updates.
- Patch affected SharePoint 2013 SP1, 2016, and 2019 deployments where applicable.
- Prioritize internet-facing or high-trust SharePoint sites first.
- Review vendor guidance before relying on compensating controls.
- Limit unnecessary low-privilege SharePoint access where operationally feasible.
Validation and detection
- Inventory SharePoint versions and editions against the affected product list.
- Confirm installed SharePoint build levels against Microsoft’s CVE guidance.
- Verify whether affected servers are internet-facing or broadly accessible.
- Review authentication groups for excessive low-privilege access.
- Document patch status and any vendor-noted exceptions.
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.
CVE-2021-1641 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
- Medium
- CVSS
- 4.6 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/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.
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:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C2.12.5Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.6MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- Microsoft SharePoint Server Spoofing VulnerabilityCVE reference · vendor-advisory
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1641CVE reference · x_refsource_MISC, x_transferred
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.