VulnerabilityPublished 12 Sep 2023Updated 30 Oct 2025

CVE-2023-36761: Microsoft Office 2019 · Improper Input Validation

Affects Microsoft Office 2019Source CVE Database V5

Exploited in the wild · KEV due 3 Oct 2023 · public exploit available · 19% EPSS : apply the vendor's fix or mitigations to Microsoft Office 2019 now.

Data as of 26 Oct 2026, 11:07 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

KEV deadline: 3 Oct 2023 US federal agencies must patch by this date; a sensible deadline for everyone else.
EPSS: 19.5% chance of exploitation in 30 days – higher than 97% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:P/RL:O/RC:C

Base metrics

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Temporal metrics

Exploit Code Maturity: Proof-of-Concept
Remediation Level: Official Fix
Report Confidence: Confirmed

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.
Exploit Code Maturity: Proof-of-Concept: Proof-of-concept exploit code is available, or an attack demonstration is not practical for most systems. The code or technique is not functional in all situations and may require substantial modification by a skilled attacker.
Remediation Level: Official Fix: A complete vendor solution is available. Either the vendor has issued an official patch, or an upgrade is available.
Report Confidence: Confirmed: Detailed reports exist, or functional reproduction is possible (functional exploits may provide this). Source code is available to independently verify the assertions of the research, or the author or vendor of the affected code has confirmed the presence of the vulnerability.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

Disclosed: evidence found.
CVE published 12 Sep 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
CVSS exploit maturity: proof of concept public
Exploited in the wildExploited: evidence found.
Listed in CISA KEV the same day as disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

CVE ID reserved
by Microsoft Corporation
27 Jun 202315:11 UTC, 77 days before disclosure
CVE published
on cve.org
12 Sep 202316:58 UTC, t = 0
Added to CISA KEV (opens in a new tab)
exploitation confirmed
12 Sep 2023, the same day as disclosure
KEV remediation due
US federal deadline
3 Oct 2023, 21 days after disclosure

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Affected software

Product	Affected	Fixed in
Microsoft Microsoft Office 2019	Affected =19.0.0	Fixed in–

Description

Microsoft Word Information Disclosure Vulnerability

Impact

For European organizations, this vulnerability poses a risk of sensitive information leakage if users open malicious Word documents. This could lead to exposure of confidential business data, intellectual property, or personal information, potentially resulting in reputational damage, regulatory penalties under GDPR, and competitive disadvantages. Sectors such as government, finance, healthcare, and critical infrastructure are particularly vulnerable due to the sensitivity of their data and the high usage of Microsoft Office products. Since exploitation requires user interaction, the risk is somewhat mitigated by user awareness but remains significant given the prevalence of phishing attacks. The absence of known exploits reduces immediate risk, but the medium severity score and potential for future exploitation necessitate proactive measures. The vulnerability does not affect system integrity or availability, so it is less likely to cause operational disruption but can still undermine confidentiality.

Mitigation

1. Educate users to be vigilant about opening Word documents from untrusted or unexpected sources, emphasizing the risk of phishing and social engineering. 2. Disable or restrict macros and external content loading in Microsoft Word to reduce attack surface. 3. Employ email filtering and attachment scanning to detect and block malicious documents before reaching end users. 4. Use endpoint protection solutions with behavior-based detection to identify suspicious document activity. 5. Monitor security advisories from Microsoft closely and prepare to deploy patches immediately upon release. 6. Implement network segmentation and data loss prevention (DLP) controls to limit the impact of any information disclosure. 7. Consider using application whitelisting or sandboxing for document handling in high-risk environments. 8. Regularly audit and update security policies related to document handling and user privileges. These steps go beyond generic advice by focusing on user behavior, technical controls specific to document handling, and organizational preparedness.

CWE-20Improper Input Validation (opens in a new tab)
Class weaknessLikelihood of exploit: HighCWE Top 25 (2025): #18OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design · Attack Surface Reduction
Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build "recognizers" for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of…
Architecture and Design · Libraries or Frameworks
Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
Injection Prevention (opens in a new tab)
SQL Injection Prevention (opens in a new tab)
Injection Prevention in Java (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Buffer Overflow via Environment Variables (opens in a new tab)
Server Side Include (SSI) Injection (opens in a new tab)
Cross Zone Scripting (opens in a new tab)
Command Line Execution through SQL Injection (opens in a new tab)
Object Relational Mapping Injection (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-668Exposure of Resource to Wrong Sphere (opens in a new tab)
Class weaknessOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product exposes a resource to the wrong control sphere, providing unintended actors with inappropriate access to the resource.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
OWASP Cheat Sheets
Authorization (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

Timeline

What to do

Affected software

Description

AI analysisMachine-generated, updated 31 Oct 2025, 04:36 UTC

WeaknessesCWE-20, CWE-668

Technical details

References

Community reviews

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