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.
Metrics
Affected Vendors & Products
References
History
Wed, 03 Jun 2026 14:30:00 +0000
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ssvc
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Wed, 03 Jun 2026 11:15:00 +0000
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| 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 |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: openjs
Published:
Updated: 2026-06-03T13:19:32.922Z
Reserved: 2026-03-28T17:42:51.328Z
Link: CVE-2026-5078
Updated: 2026-06-03T13:19:27.190Z
Status : Received
Published: 2026-06-03T08:16:19.743
Modified: 2026-06-03T08:16:19.743
Link: CVE-2026-5078
No data.
OpenCVE Enrichment
Updated: 2026-06-03T12:30:26Z