Security readout for executives and security teams
Plain-English summary
CVE-2021-31178 is a Microsoft Office information disclosure vulnerability. The main business concern is exposure of confidential data, not system takeover. It requires user interaction and is rated medium, but confidentiality impact is high in the supplied CVSS data.
Executive priority
Treat as a normal-priority patching item with confidentiality relevance. Escalate priority for teams handling sensitive documents, external submissions, or regulated data.
Technical view
The supplied CVSS v3.1 vector is AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N, score 5.5. This indicates local attack conditions, low complexity, no privileges required, required user interaction, unchanged scope, high confidentiality impact, and no stated integrity or availability impact.
Likely exposure
Likely exposure is unpatched affected Microsoft Office, Excel, Microsoft 365 Apps for Enterprise, Office Online Server, and Office Web Apps Server versions listed in the source bundle. Exposure depends on product presence and update status.
Exploitation context
The bundle does not identify active exploitation, and KEV is false. The evidence supports user interaction as required, but does not provide exploit mechanics, public exploit status, or attacker tradecraft details.
Researcher notes
The source bundle lacks CWE, exploit details, and product-specific fixed build data. Research should stay anchored to Microsoft advisory metadata, affected CPEs, and CVSS semantics unless additional authoritative evidence is provided.
Mitigation direction
- Review Microsoft MSRC guidance for the applicable official fix.
- Patch affected Microsoft Office and server products where applicable.
- Prioritize systems handling sensitive documents or external files.
- Limit handling of untrusted Office files until updates are confirmed.
Validation and detection
- Inventory affected Microsoft Office and Excel versions in the environment.
- Check Office Online Server and Office Web Apps Server deployments.
- Confirm patch status against the Microsoft advisory.
- Validate whether Microsoft 365 Apps clients are current.
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-2021-31178 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
- 5.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/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:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C1.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.5MediumVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31178CVE reference · x_refsource_MISC
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.