SSRF and Arbitrary File Read Privilege Escalation in Microsoft Exchange Server
CVE-2026-45504 is a high-severity server-side request forgery vulnerability in on-premises Microsoft Exchange Server 2016, Exchange Server 2019, and Exchange Server Subscription Edition. The vulnerable flow is in Exchange’s handling of SharePoint/WOPI document-preview URLs. Exchange helper functions involved in the preview/token acquisition chain, including GetTokenRequestWebResponse and GetWacUrl, ultimately issue requests based on attacker-influenced URL data obtained from a WOPI/OData response. Exchange parses fields including WebApplicationUrl, AccessToken, and AccessTokenTtl, but does not properly validate the URL scheme of the returned WebApplicationUrl. An attacker-controlled WOPI provider can therefore return a malicious non-HTTP URL, including a file:// URL. By using a crafted value such as file:///C:/windows/win.ini# and abusing URI fragment handling so appended OAuth parameters are ignored, Exchange can be induced to issue a FileWebRequest against a local path on the Exchange server and return the file contents through Exchange services. Microsoft classifies the issue as an elevation of privilege vulnerability because the SSRF primitive can be used to impersonate another user, access restricted information, and perform actions with elevated privileges.
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Impact, mitigation & remediation
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Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
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Remediation
Patch, then assume compromise.
Exploits
1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
Repository contains a single Python exploit script and a short README with usage example. The script targets Microsoft Exchange and implements an authenticated SSRF-to-local-file-read chain for CVE-2026-45504. It accepts target URL, attacker callback IP/port, credentials, password, and an arbitrary target file path. Execution flow: (1) start a local HTTP server to answer Exchange callback requests with crafted XML containing a file:/// URI to the desired local file; (2) authenticate to OWA via /owa/auth.owa and obtain an OWA canary token; (3) use NTLM-authenticated EWS SOAP requests to /ews/exchange.asmx to create a draft message and then attach a malicious ReferenceAttachment using ProviderType OneDrivePro with attacker-controlled ProviderEndpointUrl/AttachLongPathName; (4) call /owa/service.svc?action=GetAttachmentPreview&id=... to trigger preview generation and return the file contents; (5) print the retrieved bytes to stdout. The exploit is operational rather than a mere PoC because it automates the full chain and returns file contents, but it does not provide a generalized framework or customizable post-exploitation payload beyond arbitrary file read.
Affected products & vendors
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Recent activity
14 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A high-severity Microsoft Exchange Server vulnerability in which insufficient validation of attacker-influenced WOPI/WebApplicationUrl values enables SSRF that can be turned into arbitrary local file reads, leading to privilege escalation and broader compromise.
A server-side request forgery vulnerability in Microsoft Exchange Server that allows an authorized attacker to elevate privileges over a network.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.