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CVE-2026-5078GHSA-4VJ7-5MJ6-JM8M

morgan vulnerable to Log Forging via unneutralized control characters in :remote-user

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 1.11.0
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: partial

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • morgan morgan

    From 1.2.0 · through 1.10.1

  • morgannpm

    From 1.2.0 · fixed in 1.11.0

References 2

GitHub · expressjs/morgan

cna.openjsf.org