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.

Database specific

{
    "cna_assigner": "openjs",
    "cwe_ids": [
        "CWE-117"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5078.json"
}

References

Affected packages

Git / github.com/expressjs/morgan

Affected ranges

Type

GIT

Repo

https://github.com/expressjs/morgan

Events

Introduced

34f0479eaf433191a264c1dce2b11c521f9749c0

Fixed

e0e6f17574db56396f8e60ebb03bb7aaaeb9cc6f

Database specific

{
    "source": [
        "AFFECTED_FIELD",
        "CPE_RANGE"
    ],
    "cpe": "cpe:2.3:a:morgan_project:morgan:*:*:*:*:*:node.js:*:*",
    "extracted_events": [
        {
            "introduced": "1.2.0"
        },
        {
            "last_affected": "1.10.1"
        },
        {
            "fixed": "1.11.0"
        }
    ]
}

Affected versions

1.*

1.10.0

1.2.0

1.2.1

1.2.2

1.2.3

1.3.0

1.3.1

1.3.2

1.4.0

1.4.1

1.5.0

1.5.1

1.5.2

1.5.3

1.6.0

1.6.1

1.7.0

1.8.0

1.8.1

1.8.2

1.9.0

1.9.1

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-5078.json"