CVE-2026-55008
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedImproper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
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Surfaced from public web coverage — external links open in a new tab.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceCross-site scripting (XSS) vulnerability in Microsoft Exchange Server allows unauthenticated attackers to inject malicious scripts into web pages, potentially enabling session hijacking and spoofing attacks against users accessing the Exchange web interfaces.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 2016= 2019< 15.02.2562.045CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Exchange Server versionOpen Exchange Management Shell and run: Get-ExchangeServer | Select-Object Name, ADSite, Version, BuildNumber. Or check the build number via registry at HKLM\SOFTWARE\Microsoft\ExchangeServer\v15\SetupProperties (for Exchange 2016/2019)Affected if Build number is 15.02.xxxx for Exchange 2016/2019, or 15.02.2562.045 or lower for Subscription Edition (note: version format varies; compare full build numbers)
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Verify web interfaces are enabledCheck if OWA (Outlook Web App) and ECP (Exchange Control Panel) virtual directories are enabled by running: Get-OwaVirtualDirectory -Server <ServerName> | Select-Object Name, InternalUrl, ExternalUrl, EnabledAffected if OWA or ECP virtual directories show Enabled=True and are accessible (these web interfaces are the attack surface for XSS)
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Confirm web interface accessibilityAttempt to access OWA login page internally and externally: https://<server>/owa and https://<server>/ecp. If these respond with login pages, the web interface is exposedAffected if The /owa or /ecp endpoints return HTTP 200 with login forms, indicating the vulnerable XSS attack surface is reachable
A user is affected if their Exchange Server version falls within 2016/2019 (any build) or Subscription Edition < 15.02.2562.045 AND the OWA/ECP web interfaces are enabled and accessible.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data15.02.2562.045
Apply Microsoft security patches for Exchange Server when available; implement input validation and output encoding on affected Exchange components; consider web application firewall rules to detect XSS payloads.
- Consultation4.0 h
- Implementation8.0 h
- Testing12.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,616.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-55008 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-55008 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data