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PatchSiren cyber security CVE debrief

CVE-2026-66304 Microsoft CVE debrief

A server-side request forgery (SSRF) vulnerability exists in Skype for Business, allowing an unauthorized attacker to disclose information over a network. This issue is rated as HIGH with a CVSS score of 7.5. The vulnerability could allow attackers to access sensitive information, potentially leading to further exploitation. Defenders should assess exposure and prioritize patching to mitigate potential risks. The CVE record and NVD entry provide details on the SSRF vulnerability in Skype for Business Server.

Vendor
Microsoft
Product
Skype For Business Server
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-08
Original CVE updated
2026-09-16
Advisory published
2026-09-08
Advisory updated
2026-09-16

Who should care

Defenders and administrators responsible for Skype for Business Server deployments should assess exposure and potential impact. This includes verifying system configurations, reviewing vendor advisories, and applying patches to mitigate the vulnerability. Security teams and vulnerability management teams should prioritize this issue due to its high severity rating and potential for information disclosure.

Why it matters

Defenders should prioritize verifying exposure and assessing potential impact of the SSRF vulnerability in Skype for Business Server, especially in environments using affected versions.

  • Verify exposure and assess potential impact on information disclosure.
  • Review and apply vendor advisories and patches.
  • Monitor for potential unauthorized information disclosure.

Technical summary

The CVE record describes a server-side request forgery (SSRF) vulnerability in Skype for Business Server, which could allow an unauthorized attacker to disclose information over a network. The vulnerability is rated as HIGH with a CVSS score of 7.5. The SSRF vulnerability may allow attackers to bypass security controls and access sensitive information. Specific details on exploitation and remediation are limited, but defenders should prioritize verifying exposure and assessing potential impact.

Defensive priority

Defenders should prioritize verifying exposure and assessing potential impact, especially in environments using affected Skype for Business Server versions.

Recommended defensive actions

  • Verify exposure by checking Skype for Business Server versions and configurations.
  • Assess potential impact on information disclosure.
  • Review and apply vendor advisories and patches.

Evidence notes

The CVE record and NVD entry provide details on the SSRF vulnerability in Skype for Business Server. However, specific details on exploitation, impact, and remediation are limited.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-66304 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-66304

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-66304 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-66304

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.