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MorganApplication · Morgan Project

CVE-2026-5078

MEDIUM · 5.3 CVSS v3.1 Published 2026-06-03
Fix available
A fix is available. Upgrade to 1.11.0 or later.
See remediation →
62/100
Remediation priority · Elevated
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
Impact: The morgan logging middleware's :remote-user token extracts the Basic auth username from the Authorization request header and writes it to the log stream without neutralizing control characters. An unauthenticated attacker can send a crafted Authorization Basic header containing CR or LF bytes to inject forged log lines, breaking the one-request-per-line structure of access logs and enabling log forgery against downstream log consumers. The built-in combined, common, default, and short formats are affected, as well as any custom format that references :remote-user. Affected versions: morgan 1.2.0 through 1.10.1. Patches: upgrade to morgan 1.11.0, which neutralizes control characters in the :remote-user token output. Workarounds: use a custom format string that does not include :remote-user.

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

The morgan logging middleware's :remote-user token writes Basic auth usernames directly to log streams without neutralizing control characters. An unauthenticated attacker can inject CR (carriage return) and LF (line feed) bytes via a crafted Authorization header to forge log entries, breaking the one-request-per-line format and poisoning downstream log analysis systems. All built-in formats (combined, common, default, short) and custom formats using :remote-user are vulnerable.

MitigationUpgrade morgan to version 1.11.0 or later to enable automatic neutralization of control characters in the :remote-user token. Alternatively, use a custom format string that excludes the :remote-user token.

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
MorganApplication
Affected:>= 1.2.0, < 1.11.0

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
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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. Check installed morgan version
    Run `npm list morgan` or inspect your package.json dependencies
    Affected if Version is >= 1.2.0 and < 1.11.0
  2. Verify morgan is in use
    Search your codebase for `require('morgan')` or `import morgan` to confirm the middleware is loaded
    Affected if Morgan is imported and used as middleware
  3. Inspect logging format for :remote-user token
    Find where morgan is configured (e.g., app.use(morgan('combined'))) and examine the format string; look for :remote-user in custom formats or in predefined formats like 'combined' that include it
    Affected if The format string contains the :remote-user token
  4. Confirm application processes Authorization headers
    Check if your Express/Connect app parses Authorization headers or accepts Basic authentication credentials that could be logged
    Affected if The application processes and logs Authorization header content

You are affected if morgan version is between 1.2.0 and 1.11.0, your log format includes :remote-user, and your application handles Basic auth headers that could inject control characters into logs.

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.

dbcve · scoped
Upgrade available Upgrade to 1.11.0 or later
Fixed in 1.11.0
Interim mitigation

Upgrade morgan to version 1.11.0 or later to enable automatic neutralization of control characters in the :remote-user token. Alternatively, use a custom format string that excludes the :remote-user token.

Recommended fix High confidence

morgan 1.11.0

  1. Check current morgan version by running 'npm list morgan' or reviewing package.json
  2. Update morgan to version 1.11.0 by running 'npm install [email protected]' or updating the version in package.json
  3. Verify the upgrade was successful by running 'npm list morgan' to confirm version 1.11.0 is installed
  4. Test the application to ensure logging functionality works correctly with the upgraded package

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Morgan Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing3.0 h
  • Review / QA2.0 h
8.0 hours of engineering $1,390
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,224.

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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-2026-5078 in production — separate from our analysis above.

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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
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