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.

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History

Fri, 05 Jun 2026 10:45:00 +0000

Type Values Removed Values Added
First Time appeared Morgan
Morgan morgan
Vendors & Products Morgan
Morgan morgan

Thu, 04 Jun 2026 19:30:00 +0000

Type Values Removed Values Added
First Time appeared Morgan Project
Morgan Project morgan
CPEs cpe:2.3:a:morgan_project:morgan:*:*:*:*:*:node.js:*:*
Vendors & Products Morgan Project
Morgan Project morgan

Wed, 03 Jun 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 03 Jun 2026 11:15:00 +0000

Type Values Removed Values Added
Description 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.
Title morgan vulnerable to Log Forging via unneutralized control characters in :remote-user
Weaknesses CWE-117
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: openjs

Published:

Updated: 2026-06-03T13:19:32.922Z

Reserved: 2026-03-28T17:42:51.328Z

Link: CVE-2026-5078

cve-icon Vulnrichment

Updated: 2026-06-03T13:19:27.190Z

cve-icon NVD

Status : Analyzed

Published: 2026-06-03T08:16:19.743

Modified: 2026-06-04T19:24:21.557

Link: CVE-2026-5078

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-05T10:12:11Z

Weaknesses