VDB-400636 · CVE-2026-69621 · GCVE-0-2026-69621

Microsoft Windows up to Server 2025 Fax Service buffer overflow

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.7	$5k-$25k	0.44+

Summaryinfo

A vulnerability described as very critical has been identified in Microsoft Windows. Impacted is an unknown function of the component Fax Service. Executing a manipulation can lead to buffer overflow. This vulnerability is handled as CVE-2026-69621. It is possible to launch the attack on the local host. There is not any exploit available. It is advisable to implement a patch to correct this issue.

Detailsinfo

A vulnerability classified as very critical was found in Microsoft Windows. This vulnerability affects an unknown code block of the component Fax Service. The manipulation with an unknown input leads to a buffer overflow vulnerability. The CWE definition for the vulnerability is CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Heap-based buffer overflow in Windows Fax Service allows an authorized attacker to elevate privileges locally.

The advisory is shared for download at msrc.microsoft.com. This vulnerability was named CVE-2026-69621 since 08/03/2026. The exploitation appears to be easy. The attack needs to be approached locally. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 09/08/2026).

Applying a patch is able to eliminate this problem.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Operating System

Vendor

Microsoft

Name

Windows

Version

License

commercial

Website

Vendor: https://www.microsoft.com/
Product: https://www.microsoft.com/en-us/windows

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.9
VulDB Meta Temp Score: 7.7

VulDB Base Score: 8.8
VulDB Temp Score: 8.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.0
CNA Vector (microsoft): 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

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

Exploitinginfo

Class: Buffer overflow
CWE: CWE-120 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Timelineinfo

08/03/2026 CVE reserved
09/08/2026 +36 days Advisory disclosed
09/08/2026 +0 days VulDB entry created
09/08/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com
Product: microsoft.com

Advisory: msrc.microsoft.com
Status: Confirmed

CVE: CVE-2026-69621 (🔒)
GCVE (CVE): GCVE-0-2026-69621
GCVE (VulDB): GCVE-100-400636
scip Labs: https://www.scip.ch/en/?labs.20161215

Entryinfo

Created: 09/08/2026 23:24
Changes: 09/08/2026 23:24 (63)
Complete: 🔍
Cache ID: 216::103