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 tied to 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 such as a file:// URI. By using a fragment character (#), the attacker can neutralize appended OAuth query parameters, causing Exchange to process a path such as file:///C:/Windows/win.ini# and issue a FileWebRequest against the local filesystem. This turns the SSRF primitive into arbitrary local file read on the Exchange server and can be leveraged for elevation of privilege through Exchange services.
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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
10 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.