MSRC_CVE-2026-40421
Vulnerability from csaf_microsoft - Published: 2026-05-12 07:00 - Updated: 2026-05-12 07:00Summary
Microsoft Word Information Disclosure Vulnerability
Severity
Important
Notes
Additional Resources: To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle
Disclaimer: The information provided in the Microsoft Knowledge Base is provided \"as is\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
Customer Action: Required. The vulnerability documented by this CVE requires customer action to resolve.
CWE-73
- External Control of File Name or Path
Affected products
Fixed
10 products
| Product | Identifier | Version | Remediation |
|---|---|---|---|
|
Microsoft Word 2016 (32-bit edition) 16.0.5552.1000
Microsoft Word 2016 (32-bit edition)
|
16.0.5552.1000 | ||
|
Microsoft Word 2016 (64-bit edition) 16.0.5552.1000
Microsoft Word 2016 (64-bit edition)
|
16.0.5552.1000 | ||
|
Microsoft Office 2019 for 32-bit editions https://aka.ms/OfficeSecurityReleases
Microsoft Office 2019 for 32-bit editions
|
https://aka.ms/OfficeSecurityReleases | ||
|
Microsoft Office 2019 for 64-bit editions https://aka.ms/OfficeSecurityReleases
Microsoft Office 2019 for 64-bit editions
|
https://aka.ms/OfficeSecurityReleases | ||
|
Microsoft 365 Apps for Enterprise for 32-bit Systems https://aka.ms/OfficeSecurityReleases
Microsoft 365 Apps for Enterprise for 32-bit Systems
|
https://aka.ms/OfficeSecurityReleases | ||
|
Microsoft 365 Apps for Enterprise for 64-bit Systems https://aka.ms/OfficeSecurityReleases
Microsoft 365 Apps for Enterprise for 64-bit Systems
|
https://aka.ms/OfficeSecurityReleases | ||
|
Microsoft Office LTSC 2021 for 64-bit editions https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2021 for 64-bit editions
|
https://aka.ms/OfficeSecurityReleases | ||
|
Microsoft Office LTSC 2021 for 32-bit editions https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2021 for 32-bit editions
|
https://aka.ms/OfficeSecurityReleases | ||
|
Microsoft Office LTSC 2024 for 32-bit editions https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2024 for 32-bit editions
|
https://aka.ms/OfficeSecurityReleases | ||
|
Microsoft Office LTSC 2024 for 64-bit editions https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2024 for 64-bit editions
|
https://aka.ms/OfficeSecurityReleases |
Known affected
10 products
| Product | Identifier | Version | Remediation |
|---|---|---|---|
|
Microsoft Office LTSC 2024 for 64-bit editions <https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2024 for 64-bit editions
|
<https://aka.ms/OfficeSecurityReleases |
Vendor Fix
fix
|
|
|
Microsoft Office LTSC 2024 for 32-bit editions <https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2024 for 32-bit editions
|
<https://aka.ms/OfficeSecurityReleases |
Vendor Fix
fix
|
|
|
Microsoft Office LTSC 2021 for 32-bit editions <https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2021 for 32-bit editions
|
<https://aka.ms/OfficeSecurityReleases |
Vendor Fix
fix
|
|
|
Microsoft Office LTSC 2021 for 64-bit editions <https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2021 for 64-bit editions
|
<https://aka.ms/OfficeSecurityReleases |
Vendor Fix
fix
|
|
|
Microsoft 365 Apps for Enterprise for 64-bit Systems <https://aka.ms/OfficeSecurityReleases
Microsoft 365 Apps for Enterprise for 64-bit Systems
|
<https://aka.ms/OfficeSecurityReleases |
Vendor Fix
fix
|
|
|
Microsoft 365 Apps for Enterprise for 32-bit Systems <https://aka.ms/OfficeSecurityReleases
Microsoft 365 Apps for Enterprise for 32-bit Systems
|
<https://aka.ms/OfficeSecurityReleases |
Vendor Fix
fix
|
|
|
Microsoft Office 2019 for 64-bit editions <https://aka.ms/OfficeSecurityReleases
Microsoft Office 2019 for 64-bit editions
|
<https://aka.ms/OfficeSecurityReleases |
Vendor Fix
fix
|
|
|
Microsoft Office 2019 for 32-bit editions <https://aka.ms/OfficeSecurityReleases
Microsoft Office 2019 for 32-bit editions
|
<https://aka.ms/OfficeSecurityReleases |
Vendor Fix
fix
|
|
|
Microsoft Word 2016 (64-bit edition) <16.0.5552.1000
Microsoft Word 2016 (64-bit edition)
|
<16.0.5552.1000 |
Vendor Fix
fix
|
|
|
Microsoft Word 2016 (32-bit edition) <16.0.5552.1000
Microsoft Word 2016 (32-bit edition)
|
<16.0.5552.1000 |
Vendor Fix
fix
|
Threats
Impact
Information Disclosure
Exploit Status
Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation Less Likely
References
7 references
Acknowledgments
tiebuchen
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"text": "Important"
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"lang": "en-US",
"notes": [
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"category": "general",
"text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
"title": "Additional Resources"
},
{
"category": "legal_disclaimer",
"text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
"title": "Disclaimer"
},
{
"category": "general",
"text": "Required. The vulnerability documented by this CVE requires customer action to resolve.",
"title": "Customer Action"
}
],
"publisher": {
"category": "vendor",
"contact_details": "secure@microsoft.com",
"name": "Microsoft Security Response Center",
"namespace": "https://msrc.microsoft.com"
},
"references": [
{
"category": "self",
"summary": "CVE-2026-40421 Microsoft Word Information Disclosure Vulnerability - HTML",
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40421"
},
{
"category": "self",
"summary": "CVE-2026-40421 Microsoft Word Information Disclosure Vulnerability - CSAF",
"url": "https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-40421.json"
},
{
"category": "external",
"summary": "Microsoft Exploitability Index",
"url": "https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1"
},
{
"category": "external",
"summary": "Microsoft Support Lifecycle",
"url": "https://support.microsoft.com/lifecycle"
},
{
"category": "external",
"summary": "Common Vulnerability Scoring System",
"url": "https://www.first.org/cvss"
}
],
"title": "Microsoft Word Information Disclosure Vulnerability",
"tracking": {
"current_release_date": "2026-05-12T07:00:00.000Z",
"generator": {
"date": "2026-05-12T17:53:08.867Z",
"engine": {
"name": "MSRC Generator",
"version": "1.0"
}
},
"id": "msrc_CVE-2026-40421",
"initial_release_date": "2026-05-12T07:00:00.000Z",
"revision_history": [
{
"date": "2026-05-12T07:00:00.000Z",
"legacy_version": "1",
"number": "1",
"summary": "Information published."
}
],
"status": "final",
"version": "1"
}
},
"product_tree": {
"branches": [
{
"branches": [
{
"category": "product_version_range",
"name": "\u003chttps://aka.ms/OfficeSecurityReleases",
"product": {
"name": "Microsoft Office 2019 for 32-bit editions \u003chttps://aka.ms/OfficeSecurityReleases",
"product_id": "8"
}
},
{
"category": "product_version",
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"product": {
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"product_id": "7"
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{
"category": "product_version",
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"product": {
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"product_id": "11574"
}
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"category": "product_name",
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},
{
"branches": [
{
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"product": {
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"product_id": "6"
}
},
{
"category": "product_version",
"name": "https://aka.ms/OfficeSecurityReleases",
"product": {
"name": "Microsoft 365 Apps for Enterprise for 32-bit Systems https://aka.ms/OfficeSecurityReleases",
"product_id": "11762"
}
}
],
"category": "product_name",
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{
"branches": [
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"product": {
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"product_id": "5"
}
},
{
"category": "product_version",
"name": "https://aka.ms/OfficeSecurityReleases",
"product": {
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"product_id": "11763"
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"product_id": "4"
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},
{
"category": "product_version",
"name": "https://aka.ms/OfficeSecurityReleases",
"product": {
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"product_id": "11952"
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],
"category": "product_name",
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"product_id": "3"
}
},
{
"category": "product_version",
"name": "https://aka.ms/OfficeSecurityReleases",
"product": {
"name": "Microsoft Office LTSC 2021 for 32-bit editions https://aka.ms/OfficeSecurityReleases",
"product_id": "11953"
}
}
],
"category": "product_name",
"name": "Microsoft Office LTSC 2021 for 32-bit editions"
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"product_id": "2"
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},
{
"category": "product_version",
"name": "https://aka.ms/OfficeSecurityReleases",
"product": {
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"category": "product_name",
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"product_id": "1"
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},
{
"category": "product_version",
"name": "https://aka.ms/OfficeSecurityReleases",
"product": {
"name": "Microsoft Office LTSC 2024 for 64-bit editions https://aka.ms/OfficeSecurityReleases",
"product_id": "12421"
}
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}
],
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},
"vulnerabilities": [
{
"cve": "CVE-2026-40421",
"cwe": {
"id": "CWE-73",
"name": "External Control of File Name or Path"
},
"notes": [
{
"category": "general",
"text": "Microsoft",
"title": "Assigning CNA"
},
{
"category": "faq",
"text": "An attacker must send a user a malicious Office file and convince them to open it.",
"title": "According to the CVSS metric, user interaction is required (UI:R). What interaction would the user have to do?"
},
{
"category": "faq",
"text": "Exploiting this vulnerability could allow the disclosure of NTLM hashes.",
"title": "What type of information could be disclosed by this vulnerability?"
},
{
"category": "faq",
"text": "An attacker who successfully exploited the vulnerability could view some sensitive information (Confidentiality) but not all resources within the impacted component may be divulged to the attacker. The attacker cannot make changes to disclosed information (Integrity) or limit access to the resource (Availability).",
"title": "According to the CVSS metrics, successful exploitation of this vulnerability could lead to some loss of confidentiality (C:L),but lead to no loss of availability (A:N) and integrity (I:N)? What does that mean for this vulnerability?"
},
{
"category": "faq",
"text": "No, the Preview Pane is not an attack vector.",
"title": "Is the Preview Pane an attack vector for this vulnerability?"
}
],
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"2",
"3",
"4",
"5",
"6",
"7",
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"10"
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"references": [
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},
{
"category": "self",
"summary": "CVE-2026-40421 Microsoft Word Information Disclosure Vulnerability - CSAF",
"url": "https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-40421.json"
}
],
"remediations": [
{
"category": "vendor_fix",
"date": "2026-05-12T07:00:00.000Z",
"details": "https://aka.ms/OfficeSecurityReleases:Security Update:https://docs.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates",
"product_ids": [
"8",
"7",
"6",
"5",
"4",
"3",
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},
{
"category": "vendor_fix",
"date": "2026-05-12T07:00:00.000Z",
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"product_ids": [
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"9"
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"url": "https://support.microsoft.com/help/5002858"
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],
"scores": [
{
"cvss_v3": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 4.3,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"environmentalsScore": 0.0,
"exploitCodeMaturity": "UNPROVEN",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"remediationLevel": "OFFICIAL_FIX",
"reportConfidence": "CONFIRMED",
"scope": "UNCHANGED",
"temporalScore": 3.8,
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C",
"version": "3.1"
},
"products": [
"1",
"2",
"3",
"4",
"5",
"6",
"7",
"8",
"9",
"10"
]
}
],
"threats": [
{
"category": "impact",
"details": "Information Disclosure"
},
{
"category": "exploit_status",
"details": "Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation Less Likely"
}
],
"title": "Microsoft Word Information Disclosure Vulnerability"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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