CVE-2026-66307: CWE-191: Integer Underflow (Wrap or Wraparound) in Microsoft Skype for Business Server 2015 CU13
Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to deny service over a network.
AI Analysis
Technical Summary
This vulnerability involves an integer underflow (wrap or wraparound) condition in Skype for Business Server 2015 CU13 (version 9319.0). Exploitation can lead to denial of service by an unauthenticated attacker over the network. The CVSS 3.1 vector indicates network attack vector, low attack complexity, no privileges or user interaction required, and impacts availability only. Microsoft has published an official fix for this vulnerability.
Potential Impact
An attacker can exploit the integer underflow to cause a denial of service condition, disrupting the availability of Skype for Business Server 2015 CU13. There is no impact on confidentiality or integrity according to the CVSS vector. No known exploits are reported in the wild at this time.
Mitigation Recommendations
An official fix is available from Microsoft. Users should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66307 to remediate this vulnerability.
CVE-2026-66307: CWE-191: Integer Underflow (Wrap or Wraparound) in Microsoft Skype for Business Server 2015 CU13
Description
Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to deny service over a network.
CVSS v3.1
Score 7.5high
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves an integer underflow (wrap or wraparound) condition in Skype for Business Server 2015 CU13 (version 9319.0). Exploitation can lead to denial of service by an unauthenticated attacker over the network. The CVSS 3.1 vector indicates network attack vector, low attack complexity, no privileges or user interaction required, and impacts availability only. Microsoft has published an official fix for this vulnerability.
Potential Impact
An attacker can exploit the integer underflow to cause a denial of service condition, disrupting the availability of Skype for Business Server 2015 CU13. There is no impact on confidentiality or integrity according to the CVSS vector. No known exploits are reported in the wild at this time.
Mitigation Recommendations
An official fix is available from Microsoft. Users should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66307 to remediate this vulnerability.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- microsoft
- Date Reserved
- 2026-07-24T18:06:51.294Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- official-fix
- Vendor Advisory Urls
- [{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66307","vendor":"Microsoft"}]
Threat ID: 6aa059e1acd9273b4913b7f4
Added to database: 09/08/2026, 18:54:25 UTC
Last enriched: 09/08/2026, 19:07:27 UTC
Last updated: 09/09/2026, 02:17:38 UTC
Views: 9
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