How severe is CVE-2026-66308?

CVE-2026-66308 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-66308 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-66308?

CVE-2026-66308 primarily affects Microsoft Skype For Business Server. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-66308?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-66308 published?

CVE-2026-66308 was published on 2026-09-08 and last updated on 2026-09-16.

CVE-2026-66308

CVE-2026-66308 is a medium-severity vulnerability in Microsoft Skype For Business Server with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 1% (66th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Microsoft Skype For Business Server
Published: 2026-09-08
Last modified: 2026-09-16

Description

Out-of-bounds read in Skype for Business allows an authorized attacker to deny service over a network.

Frequently asked questions

What is CVE-2026-66308?: Out-of-bounds read in Skype for Business allows an authorized attacker to deny service over a network.
How severe is CVE-2026-66308?: CVE-2026-66308 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-66308 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-66308?: CVE-2026-66308 primarily affects Microsoft Skype For Business Server. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-66308?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-66308 published?: CVE-2026-66308 was published on 2026-09-08 and last updated on 2026-09-16.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66308

Affected products (6)

cpe:2.3:a:microsoft:skype_for_business_server:2015:cumulative_update_13:*:*:*:*:*:*
cpe:2.3:a:microsoft:skype_for_business_server:2015:cumulative_update_13_hotfix_2:*:*:*:*:*:*
cpe:2.3:a:microsoft:skype_for_business_server:2019:cumulative_update_8:*:*:*:*:*:*
cpe:2.3:a:microsoft:skype_for_business_server:2019:cumulative_update_8_hotfix1:*:*:*:*:*:*
cpe:2.3:a:microsoft:skype_for_business_server:2019:cumulative_update_8_hotfix2:*:*:*:*:*:*
cpe:2.3:a:microsoft:skype_for_business_server_subscription_edition:7.0.2046.849:*:*:*:*:*:*:*

More vulnerabilities in Microsoft Skype For Business Server

CVE-2026-66302 — Critical (CVSS 9.8): External control of file name or path in Skype for Business allows an unauthorized attacker to execute code over a…
CVE-2026-69646 — High (CVSS 8.3): Improper verification of cryptographic signature in Skype for Business allows an unauthorized attacker to perform…
CVE-2026-66307 — High (CVSS 7.5): Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to deny service over a…
CVE-2026-66304 — High (CVSS 7.5): Server-side request forgery (ssrf) in Skype for Business allows an unauthorized attacker to disclose information over a…
CVE-2023-36789 — High (CVSS 7.2): Skype for Business Remote Code Execution Vulnerability
CVE-2023-36786 — High (CVSS 7.2): Skype for Business Remote Code Execution Vulnerability

All CVEs affecting Microsoft Skype For Business Server →

Other CWE-125 (Out-of-bounds Read) vulnerabilities

CVE-2026-24826 — Critical (CVSS 10.0): Out-of-bounds Write, Divide By Zero, NULL Pointer Dereference, Use of Uninitialized Resource, Out-of-bounds Read,…
CVE-2024-22004 — Critical (CVSS 10.0): Due to length check, an attacker with privilege access on a Linux Nonsecure operating system can trigger a…
CVE-2021-41556 — Critical (CVSS 10.0): sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bounds read (in the core interpreter) that…
CVE-2021-21777 — Critical (CVSS 10.0): An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer…
CVE-2017-14451 — Critical (CVSS 10.0): An exploitable out-of-bounds read vulnerability exists in libevm (Ethereum Virtual Machine) of CPP-Ethereum. A…
CVE-2013-0767 — Critical (CVSS 10.0): The nsSVGPathElement::GetPathLengthScale function in Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and…

Browse all CWE-125 (Out-of-bounds Read) vulnerabilities →