Microsoft Exchange Server Spoofing Vulnerability
Published September 8, 2026Updated September 8, 2026
Source data
Overview
Server-side request forgery (ssrf) in Microsoft Exchange Server allows an authorized attacker to perform spoofing over a network.
Impact & technical details
Spoofing
What is the nature of the spoofing? An authenticated attacker could cause an affected Exchange server to send HTTP requests to internal or loopback systems by submitting a specially crafted internet calendar subscription. Successful exploitation could expose sensitive information returned as valid calendar content from resources reachable by the server.
According to the CVSS metric, privileges required is low (PR:L). What does that mean for this vulnerability? The attacker must be authenticated using valid Exchange user credentials.
- CVSS base score
- 6.5 / 10
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
Highest base score supplied by MSRC for this record; the vector belongs to that score. Ratings can vary by product. Microsoft Important is displayed as High; Moderate is displayed as Medium.
Affected products
- Microsoft Exchange Server 2016 Cumulative Update 23
- Microsoft Exchange Server 2019 Cumulative Update 14
- Microsoft Exchange Server 2019 Cumulative Update 15
- Microsoft Exchange Server Subscription Edition RTM
Source guidance
Remediation
The source provides update references without a separate remediation summary. Review the applicable update links below.
At least one Microsoft vendor-fix reference is available. Check each affected product for its applicable update, prerequisites, and supported version.
GTP recommendation · Rule-based guidance
Recommended next step
Review affected Microsoft products and apply the applicable security updates through your organization's normal patch-management process. Confirm availability and prerequisites in the Microsoft advisory.
Authoritative sources & updates
Findings and update information come from the linked publishers. GTP compiles the public record and provides the recommendation above. CVSS ratings shown here come from Microsoft. NVD references provide additional public context.
- Microsoft Security Response Center (opens in a new tab)
- Microsoft remediation guidance (opens in a new tab)
- Microsoft remediation guidance (opens in a new tab)
- Microsoft remediation guidance (opens in a new tab)
- Microsoft security update · 5121608 (opens in a new tab)
- Microsoft remediation guidance (opens in a new tab)
Managed by GTP?
Griffin Technology Partners managed customers may receive additional environment-specific security guidance and remediation assistance through their managed services relationship.
Security bulletins are provided for informational purposes and compiled from authoritative public sources. Vulnerability applicability varies by environment. Validate affected products, configuration, compatibility requirements, and vendor guidance before making production changes.