CVE-2026-5078
Impact: The morgan logging middleware's :remote-user token extracts the Basic auth username from the Authorization request header and writes
CVSS
5.3
Medio
EPSS
0.3%
p25
KEV
—
Exploit Today
8
0-100
Publicado: 3 jun 2026 · Última mod.: 22 jul 2026 · CWE-117
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.