{"cve":"CVE-2026-5078","nvd":{"published":"2026-06-03T08:16:19.743","modified":"2026-07-22T19:10:00.120","status":"Analyzed","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","score":5.3},"cwes":["CWE-117"],"references":["https://cna.openjsf.org/security-advisories.html","https://github.com/expressjs/morgan/security/advisories/GHSA-4vj7-5mj6-jm8m"],"products":["morgan_project:morgan"],"source":"nvd","synced_at":"2026-10-19T22:37:48.043517290+00:00"},"epss":{"cve":"CVE-2026-5078","score":0.00332,"percentile":0.26454,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-4vj7-5mj6-jm8m","url":"https://osv.dev/vulnerability/GHSA-4vj7-5mj6-jm8m","summary":"morgan vulnerable to Log Forging via unneutralized control characters in :remote-user","modified":"2026-09-10T03:51:10.338435570Z","packages":[{"ecosystem":"npm","name":"morgan","purl":"pkg:npm/morgan","ranges":[">=1.2.0 <1.11.0"],"fixed":["1.11.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}