Vulnerability Details CVE-2026-5078
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 11.7%
CVSS Severity
CVSS v3 Score 5.3
References
Products affected by CVE-2026-5078
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cpe:2.3:a:morgan_project:morgan:1.10.0
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cpe:2.3:a:morgan_project:morgan:1.10.1
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cpe:2.3:a:morgan_project:morgan:1.2.0
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cpe:2.3:a:morgan_project:morgan:1.2.1
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cpe:2.3:a:morgan_project:morgan:1.2.2
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cpe:2.3:a:morgan_project:morgan:1.2.3
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cpe:2.3:a:morgan_project:morgan:1.3.0
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cpe:2.3:a:morgan_project:morgan:1.3.1
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cpe:2.3:a:morgan_project:morgan:1.3.2
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cpe:2.3:a:morgan_project:morgan:1.4.0
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cpe:2.3:a:morgan_project:morgan:1.4.1
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cpe:2.3:a:morgan_project:morgan:1.5.0
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cpe:2.3:a:morgan_project:morgan:1.5.1
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cpe:2.3:a:morgan_project:morgan:1.5.2
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cpe:2.3:a:morgan_project:morgan:1.5.3
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cpe:2.3:a:morgan_project:morgan:1.6.0
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cpe:2.3:a:morgan_project:morgan:1.6.1
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cpe:2.3:a:morgan_project:morgan:1.7.0
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cpe:2.3:a:morgan_project:morgan:1.8.0
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cpe:2.3:a:morgan_project:morgan:1.8.1
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cpe:2.3:a:morgan_project:morgan:1.8.2
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cpe:2.3:a:morgan_project:morgan:1.9.0
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cpe:2.3:a:morgan_project:morgan:1.9.1