Microsoft Office up to LTSC 2024 heap-based overflow

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.1$0-$5k0.00

Summaryinfo

A vulnerability has been found in Microsoft Office up to LTSC 2024 and classified as critical. Affected by this issue is some unknown functionality. Performing a manipulation results in heap-based overflow. This vulnerability is reported as CVE-2026-40363. The attack is possible to be carried out remotely. No exploit exists. It is suggested to install a patch to address this issue.

Detailsinfo

A vulnerability classified as critical has been found in Microsoft Office up to LTSC 2024. This affects an unknown part. The manipulation with an unknown input leads to a heap-based overflow vulnerability. CWE is classifying the issue as CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.

The weakness was disclosed 05/12/2026 as confirmed security update guide (Website). The advisory is shared at msrc.microsoft.com. This vulnerability is uniquely identified as CVE-2026-40363. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 05/20/2026).

The vulnerability scanner Nessus provides a plugin with the ID 314350 (Security Updates for Microsoft Office Products (May 2026)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 16.0.10417.20128 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The best possible mitigation is suggested to be patching the affected component. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (314350). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.7
VulDB Meta Temp Score: 7.1

VulDB Base Score: 6.3
VulDB Temp Score: 5.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 8.4
Vendor Vector (Microsoft): 🔒

CNA Base Score: 8.4
CNA Vector (Microsoft): 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Heap-based overflow
CWE: CWE-122 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Yes

Availability: 🔒
Status: Unproven

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 314350
Nessus Name: Security Updates for Microsoft Office Products (May 2026)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

Reaction Time: 🔒
0-Day Time: 🔒
Exposure Time: 🔒

Upgrade: Office 16.0.10417.20128

Timelineinfo

05/12/2026 VulDB entry created
05/12/2026 +0 days Advisory disclosed
05/12/2026 +0 days Countermeasure disclosed
05/20/2026 +7 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com

Advisory: msrc.microsoft.com
Status: Confirmed

CVE: CVE-2026-40363 (🔒)
GCVE (CVE): GCVE-0-2026-40363
GCVE (VulDB): GCVE-100-363177

Entryinfo

Created: 05/12/2026 19:37
Updated: 05/20/2026 09:21
Changes: 05/12/2026 19:37 (23), 05/12/2026 19:38 (10), 05/12/2026 19:41 (36), 05/13/2026 08:33 (2), 05/20/2026 09:21 (12)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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