VDB-345299 · CVE-2026-21527 · GCVE-0-2026-21527

Microsoft Exchange Server clickjacking

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.
5.6	$5k-$25k	0.00

Summaryinfo

A vulnerability has been found in Microsoft Exchange Server and classified as problematic. This impacts an unknown function. The manipulation leads to clickjacking. This vulnerability is traded as CVE-2026-21527. It is possible to initiate the attack remotely. There is no exploit available. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability was found in Microsoft Exchange Server and classified as problematic. This issue affects an unknown part. The manipulation with an unknown input leads to a clickjacking vulnerability. Using CWE to declare the problem leads to CWE-451. The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks. Impacted is integrity. The summary by CVE is:

User interface (ui) misrepresentation of critical information in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.

The weakness was shared 02/10/2026 as confirmed security update guide (Website). It is possible to read the advisory at msrc.microsoft.com. The identification of this vulnerability is CVE-2026-21527. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 02/11/2026). The attack technique deployed by this issue is T1566.003 according to MITRE ATT&CK.

Applying a patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

Groupware Software

Vendor

Microsoft

Name

Exchange Server

Version

License

commercial

Website

Vendor: https://www.microsoft.com/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.1
VulDB Meta Temp Score: 5.6

VulDB Base Score: 5.3
VulDB Temp Score: 4.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 6.5
Vendor Vector (Microsoft): 🔒

CNA Base Score: 6.5
CNA Vector (Microsoft): 🔒

CVSSv2info

AV	AC	Au	C	I	A
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💳	💳	💳	💳	💳	💳
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Clickjacking
CWE: CWE-451
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Unproven

EPSS Score: 🔒
EPSS Percentile: 🔒

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: 🔍

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

Timelineinfo

02/10/2026 VulDB entry created
02/10/2026 +0 days Advisory disclosed
02/10/2026 +0 days Countermeasure disclosed
02/11/2026 +1 days VulDB entry last update