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.
References
Configurations
No configuration.
History
03 Jun 2026, 08:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-06-03 08:16
Updated : 2026-06-04 16:40
NVD link : CVE-2026-5078
Mitre link : CVE-2026-5078
CVE.ORG link : CVE-2026-5078
JSON object : View
Products Affected
No product.
CWE
CWE-117
Improper Output Neutralization for Logs
