Security Resilience

CVE-2026-65813

SSRF in Microsoft Exchange Server 2016 … 2019

SSRF
Published
11 August 2026
Modified
17 August 2026
Patch / advisory
View advisory
CVSS Score v3.1 6.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
EPSS Score 0.0094 61th percentile
Risk Priority 52 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). EPSS, Forum of Incident Response and Security Teams (FIRST), epss.first.org. Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-65813 is a medium-severity SSRF (CWE-918) vulnerability in Microsoft Exchange Server. Its CVSS base score is 6.5 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Proxy (T1090); ranked in the top 39% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-4 (Information Flow Enforcement) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability Data

Server-side request forgery (ssrf) in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.

CWE(s)
CWE-918

Related Threats

MITRE ATT&CK Enterprise Techniques

MITRE ATT&CK v20.0

T1090 Proxy Command And Control
Adversaries may use a connection proxy to direct network traffic between systems or act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure.
attack.mitre.org →
T1528 Steal Application Access Token Credential Access
Adversaries can steal application access tokens as a means of acquiring credentials to access remote systems and resources.
attack.mitre.org →
T1552 Unsecured Credentials Credential Access
Adversaries may search compromised systems to find and obtain insecurely stored credentials.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1552.005 Cloud Instance Metadata API Credential Access
Adversaries may attempt to access the Cloud Instance Metadata API to collect credentials and other sensitive data.
attack.mitre.org →
T1018 Remote System Discovery Discovery
Adversaries may attempt to get a listing of other systems by IP address, hostname, or other logical identifier on a network that may be used for Lateral Movement from the current system.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-45502Same product: Microsoft Exchange Server
CVE-2026-45504Same product: Microsoft Exchange Server
CVE-2026-45501Same product: Microsoft Exchange Server
CVE-2026-45503Same product: Microsoft Exchange Server
CVE-2026-62913Same product: Microsoft Exchange Server
CVE-2026-62911Same product: Microsoft Exchange Server
CVE-2026-55007Same product: Microsoft Exchange Server
CVE-2021-26855Same product: Microsoft Exchange Server
CVE-2021-34473Same product: Microsoft Exchange Server
CVE-2025-25006Same product: Microsoft Exchange Server

Affected Assets

microsoft
exchange server
2016, 2019
microsoft
exchange server subscription edition
≤ 15.02.2562.046

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.3.6
  • V1.5.3
  • V5.3.2
  • V10.4.7

Mitigating Controls (NIST 800-53 r5)

Our mappings, made for this CVE.

AC-4 Information Flow Enforcement good match

Information flow enforcement can restrict which destinations the server is allowed to contact on behalf of users.

SI-10 Information Input Validation good match

Input validation directly stops untrusted URLs from being accepted and fetched without destination checks.

SC-7 Boundary Protection partial match

Boundary protection limits the network reach of server-initiated requests even if SSRF occurs.

Mitigating Controls (NIST CSF 2.0)

Our mappings, derived directly from the weakness types (CWEs) cited in the NVD entry via our CWE→CSF cross-walk — links open the control.

PR.PS-06 mostly match
blocks

Secure development practices directly include input validation and destination allow-listing that prevent SSRF.

DE.CM-09 partial match
blocks

Runtime monitoring of web applications and services can detect anomalous outbound requests indicative of SSRF.

ID.RA-01 partial match
blocks

Vulnerability identification processes can discover and record SSRF flaws in web applications.

PR.IR-01 partial match
blocks

Network segmentation and egress controls can limit the damage from successful SSRF requests.

Mitigating Controls (ISO/IEC 27001:2022 Annex A)

Our mappings, derived directly from the weakness types (CWEs) cited in the NVD entry via our CWE→ISO cross-walk — links open the control.

A.8.22 Segregation of networks partial match
blocks

Network segregation with gateway controls blocks SSRF exploitation against internal network resources (internal admin panels, cross-domain port scanning, internal services), which is a major portion of the weakness's damage surface, but the weakness remains exploitable for external destinations, localhost services, and cloud metadata endpoints that the segregation does not reach.

A.8.28 Secure coding partial match
prevents

A.8.28 mandates secure coding principles that include URL/destination validation and allowlisting practices which, where followed, prevent SSRF from being introduced; but the clause is a practice-based control whose effect depends on developer implementation rigor, so it catches only a minority of instances — the same reading that graded A.8.28 -> CWE-502 and A.8.28 -> CWE-79 at `partial`, and the clause's declared ceiling on this verb.

References