Microsoft Skype for Business Server 2015 CU13/2019 CU8/Subscription Edition CU1 integer underflow

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.3$5k-$25k0.00+

Summaryinfo

A vulnerability, which was classified as critical, was found in Microsoft Skype for Business Server 2015 CU13/2019 CU8/Subscription Edition CU1. Affected is an unknown function. Executing a manipulation can lead to integer underflow. The identification of this vulnerability is CVE-2026-66307. The attack may be launched remotely. There is no exploit available. A patch should be applied to remediate this issue.

Detailsinfo

A vulnerability has been found in Microsoft Skype for Business Server 2015 CU13/2019 CU8/Subscription Edition CU1 and classified as critical. This vulnerability affects some unknown functionality. The manipulation with an unknown input leads to a integer underflow vulnerability. The CWE definition for the vulnerability is CWE-191. The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result. As an impact it is known to affect availability. CVE summarizes:

Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to deny service over a network.

The advisory is available at msrc.microsoft.com. This vulnerability was named CVE-2026-66307 since 07/24/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 09/08/2026).

Applying a patch is able to eliminate this problem.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.5
VulDB Meta Temp Score: 7.3

VulDB Base Score: 7.5
VulDB Temp Score: 7.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (microsoft): 🔒

CVSSv2info

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

Exploitinginfo

Class: Integer underflow
CWE: CWE-191 / CWE-189
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

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

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Timelineinfo

07/24/2026 CVE reserved
09/08/2026 +46 days Advisory disclosed
09/08/2026 +0 days VulDB entry created
09/08/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com

Advisory: msrc.microsoft.com
Status: Confirmed

CVE: CVE-2026-66307 (🔒)
GCVE (CVE): GCVE-0-2026-66307
GCVE (VulDB): GCVE-100-400234
scip Labs: https://www.scip.ch/en/?labs.20140918

Entryinfo

Created: 09/08/2026 21:10
Changes: 09/08/2026 21:10 (62)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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