Improper Output Neutralization for Logs Affecting morgan package, versions >=1.2.0 <1.11.0
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published3 Jun 2026
- disclosed3 Jun 2026
- creditYuki Matsuhashi
Introduced: 3 Jun 2026
CVE-2026-5078 (opens in a new tab)How to fix?
Upgrade morgan to version 1.11.0 or higher.
Overview
morgan is a HTTP request logger middleware for node.js.
Affected versions of this package are vulnerable to Improper Output Neutralization for Logs via the :remote-user token, which extracts the Basic auth username from the Authorization header and writes it to the log stream without neutralizing control characters. An attacker can inject forged log lines by sending crafted Authorization headers containing CR or LF bytes, potentially breaking the one-request-per-line structure of access logs and misleading downstream log consumers.
Workaround
This vulnerability can be mitigated by using a custom format string that does not include :remote-user.