{"id":"CVE-2026-5078","summary":"morgan vulnerable to Log Forging via unneutralized control characters in :remote-user","details":"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.","aliases":["GHSA-4vj7-5mj6-jm8m"],"modified":"2026-07-16T03:48:36.672111641Z","published":"2026-06-03T05:56:49.512Z","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":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5078.json"},{"type":"ADVISORY","url":"https://github.com/expressjs/morgan/security/advisories/GHSA-4vj7-5mj6-jm8m"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-5078"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/expressjs/morgan","events":[{"introduced":"34f0479eaf433191a264c1dce2b11c521f9749c0"},{"fixed":"e0e6f17574db56396f8e60ebb03bb7aaaeb9cc6f"}],"database_specific":{"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"}],"source":["AFFECTED_FIELD","CPE_RANGE"]}}],"versions":["1.10.0","1.9.1","1.9.0","1.8.2","1.8.1","1.8.0","1.7.0","1.6.1","1.6.0","1.5.3","1.5.2","1.5.1","1.5.0","1.4.1","1.4.0","1.3.2","1.3.1","1.3.0","1.2.3","1.2.2","1.2.1","1.2.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-5078.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"}]}