HotmailApplication · Microsoft

CVE-2000-0081

HIGH · 10.0 CVSS v2.0 Published 2000-01-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
Hotmail does not properly filter JavaScript code from a user's mailbox, which allows a remote attacker to execute the code by using hexadecimal codes to specify the javascript: protocol, e.g. jAvascript.

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 · high confidence

Hotmail failed to filter or sanitize JavaScript code embedded in user mailbox content, allowing attackers to inject malicious scripts by using hexadecimal HTML character encoding (e.g., A to represent 'A' in 'javascript:') to bypass basic text filters. This enabled execution of arbitrary JavaScript in the victim's browser session, potentially allowing session hijacking, cookie theft, and unauthorized actions.

MitigationImplement proper input validation and output encoding/sanitization for all user-supplied content, including HTML entity encoding for special characters and Content Security Policy (CSP) headers to restrict script execution sources.

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
HotmailApplication
Affected:all versions

CVSS 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
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:L/Au:N/C:C/I:C/A:C

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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify if you are running Microsoft Hotmail
    Check your installed email server software and verify it is Microsoft Hotmail specifically. Look for any legacy Hotmail installations or derivatives in your environment.
    Affected if The system is Microsoft Hotmail (all versions were affected)
  2. Determine if mailbox content rendering is enabled
    Check if the email system displays HTML content from incoming emails to users. Look for settings related to HTML email rendering, preview panes, or message display options.
    Affected if HTML content rendering in mailboxes is enabled and the system processes user-supplied content
  3. Check for HTML entity encoding filtering
    Inspect the email content filtering pipeline to determine if hexadecimal HTML character entities (format: &#xNN;) are being filtered, neutralized, or encoded before display. Review the sanitization logic for incoming email content.
    Affected if The filtering system does not handle hexadecimal HTML character encoding (&#xNN; sequences) and allows them to pass through unchanged
  4. Verify if script tags can be injected via encoded characters
    Test the email system by sending a message containing encoded characters that form JavaScript protocol handlers (e.g., encoded 'javascript:' using javascript) and observe if they execute in the recipient's browser.
    Affected if Hexadecimal-encoded JavaScript protocol handlers execute in the browser context rather than being neutralized

You are affected if you are running Microsoft Hotmail with HTML email rendering enabled and your content filtering does not neutralize hexadecimal HTML character encoding sequences that could embed executable JavaScript.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement proper input validation and output encoding/sanitization for all user-supplied content, including HTML entity encoding for special characters and Content Security Policy (CSP) headers to restrict script execution sources.

Fix this in Hotmail Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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Scan for this in your stack

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dbcve dependency scanner

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2000-0081 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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