Cyber Resilience

CVE-2025-49696

Memory Safety in Microsoft Office Long Term Servicing Channel 2021 … 2024

Published
08 July 2025
Modified
17 June 2026
Patch / advisory
CVSS Score v3.1 8.4
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0056 44th percentile
Risk Priority 63 floored blend · peak EPSS

Summary

CVE-2025-49696 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Microsoft Office Long Term Servicing Channel. Its CVSS base score is 8.4 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 44th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2025-49696 is an out-of-bounds read vulnerability affecting Microsoft Office, mapped to CWE-122 (Heap-based Buffer Overflow) and CWE-125 (Out-of-bounds Read). Published on 2025-07-08, it carries a CVSS v3.1 base score of 8.4 (AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H). The issue enables an unauthorized attacker to execute code locally on the affected system.

A local attacker can exploit this vulnerability with low attack complexity, requiring no privileges or user interaction. Upon successful exploitation, the attacker achieves high-impact effects, gaining unauthorized code execution that fully compromises confidentiality, integrity, and availability on the local system.

Microsoft's update guide provides details on mitigation and patches for CVE-2025-49696, available at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-49696. Security practitioners should consult this advisory for deployment instructions.

EU & UK References

Vulnerability Data

Out-of-bounds read in Microsoft Office allows an unauthorized attacker to execute code locally.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
T1211 Exploitation for Stealth Stealth
Adversaries may exploit vulnerabilities to evade detection by hiding activity, suppressing logging, or operating within trusted or unmonitored components.
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-40363Same product: Microsoft 365 Apps
CVE-2025-47162Same product: Microsoft 365 Apps
CVE-2025-49697Same product: Microsoft 365 Apps
CVE-2023-33152Same product: Microsoft 365 Apps
CVE-2023-28311Same product: Microsoft 365 Apps
CVE-2023-33146Same product: Microsoft 365 Apps
CVE-2024-20677Same product: Microsoft 365 Apps
CVE-2023-29344Same product: Microsoft 365 Apps
CVE-2023-21738Same product: Microsoft 365 Apps
CVE-2025-27752Same product: Microsoft 365 Apps

Affected Assets

microsoft
365 apps
all versions
microsoft
365 copilot
all versions
microsoft
office
2016, 2019
microsoft
office long term servicing channel
2021, 2024

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)

Validate
Prove the fix (OWASP ASVS)
  • V1.4.1

Mitigating Controls (NIST 800-53 r5) AI

Developer testing and evaluation (including fuzzing and memory-error detectors) can discover heap overflows after they have been coded.

Input validation enforces bounds checking on data written to heap buffers, directly stopping the overflow condition from being introduced.

Security engineering principles require use of memory-safe constructs and bounds-checked allocation routines that avoid introducing heap overflows.

Process isolation confines the effects of an out-of-bounds read to the compromised process.

Memory-protection mechanisms limit the ability of a heap overflow to execute attacker-controlled code or corrupt adjacent structures.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 full match
prevents

Secure-development practices directly require bounds checking and safe memory handling that prevent heap overflows.

ID.RA-01 partial match
prevents

Vulnerability scanning and recording can discover heap-overflow flaws but does not prevent their introduction in code.

PR.PS-02 partial match
prevents

Timely patching removes known heap-overflow instances after they exist.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

finds

Security testing in development and acceptance can detect heap overflows before release.

A.8.15 Logging partial match
finds

Logging can record evidence of an out-of-bounds read but does not prevent the weakness itself.

prevents

Secure development lifecycle mandates practices that reduce the likelihood of introducing heap overflows.

prevents

Application security requirements can specify bounds-checking and safe memory APIs that mitigate heap overflows.

prevents

Secure architecture and engineering principles include memory-safety and input-validation controls that address heap overflows.

prevents

Secure coding standards directly prescribe techniques (safe functions, bounds checks) that prevent heap-based buffer overflows.

References