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.

Affected: npm: morgan

### Impact

Morgan's `:remote-user` token extracts the Basic auth username from the `Authorization` header and writes it to the log stream without neutralizing control characters. An attacker can send a crafted `Authorization: Basic` header containing CR/LF characters to inject forged log lines, corrupting the one-request-per-line structure of access logs.

The built-in `combined`, `common`, `default`, and `short` formats are affected, as well as any custom format that includes `:remote-user`.

### Patches

Users should upgrade to version 1.11.0.

### Workarounds

Use a custom format string that does not include `:remote-user`.

morgan: morgan: Log forgery due to unneutralized control characters undici: Undici: Response queue poisoning on reused keep-alive sockets can lead to incorrect response delivery. undici: undici: Information disclosure and data integrity issues due to incorrect Socks5ProxyAgent connection routing undici: Undici: Information disclosure due to improper cache-control header parsing undici: undici vulnerable to HTTP header injection via Set-Cookie percent-decoding undici: undici: Man-in-the-Middle attack via ignored TLS options with SOCKS5 proxy undici: undici: Weakening of cookie SameSite policy due to incorrect parsing of Set-Cookie header undici: undici: Denial of Service due to unbounded memory growth via WebSocket frames js-yaml: js-yaml: Denial of Service via crafted YAML merge keys js-yaml: js-yaml: Denial of Service via crafted YAML documents

Affected: Ubuntu:22.04:LTS: node-morgan, Ubuntu:24.04:LTS: node-morgan, Ubuntu:25.10: node-morgan, Ubuntu:26.04:LTS: node-morgan

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.