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CVE-2026-69378 Microsoft CVE debrief

Microsoft Exchange Server is vulnerable to uncontrolled recursion, allowing an unauthorized attacker to deny service over a network. This CVE was published on 2026-09-08T18:18:58.543Z and was last modified on 2026-09-29T15:54:45.013Z. The NVD entry is currently Analyzed. The vulnerability affects Microsoft Exchange Server, which is a widely used email server software. The uncontrolled recursion vulnerability could allow an attacker to cause a denial of service (DoS) attack, potentially disrupting email services. Exchange Server administrators and security teams should be aware of this vulnerability and take action to prevent potential service denial attacks. It is essential to note

Vendor
Microsoft
Product
Microsoft Exchange Server 2016 Cumulative Update 23
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-08
Original CVE updated
2026-09-29
Advisory published
2026-09-08
Advisory updated
2026-09-29

Who should care

Exchange Server administrators and security teams responsible for patching and vulnerability management should be aware of this vulnerability and take action to prevent potential service denial attacks.

Why it matters

CVE-2026-69378 is a high-severity vulnerability in Microsoft Exchange Server that allows an unauthorized attacker to deny service over a network. Exchange Server administrators and security teams should prioritize patching and monitoring to prevent potential service denial attacks.

  • Verify and apply patches for Microsoft Exchange Server to prevent potential service denial.
  • Monitor Exchange Server logs for signs of potential attacks.
  • Review incident response plans to address potential service denial attacks.

Technical summary

CVE-2026-69378 is a high-severity vulnerability in Microsoft Exchange Server that allows an unauthorized attacker to deny service over a network. The vulnerability has a CVSS score of 7.5 and is classified as CWE-674. The vulnerability is caused by uncontrolled recursion in Microsoft Exchange Server, which can be exploited by an attacker to cause a denial of service (DoS) attack. The vulnerability affects Microsoft Exchange Server, and Exchange Server administrators and security teams should prioritize patching and monitoring to prevent potential service denial.

Defensive priority

Exchange Server administrators should prioritize patching to prevent potential service denial.

Recommended defensive actions

  • Apply patches for Microsoft Exchange Server as recommended by the vendor.
  • Review and update incident response plans to address potential service denial attacks.
  • Monitor Exchange Server logs for signs of potential attacks.

Evidence notes

The CVE record and NVD detail page provide information on the vulnerability, but do not specify which versions are affected or provide remediation details.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-69378 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-69378

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

  • CVE-2026-69378 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-69378

    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.