CVE-2026-5078

5.3 MEDIUM

Impact: The morgan logging middleware's :remote-user token extracts the Basic auth username from the Authorization request header and wri...

Published: 2026-06-03 · Last updated: 2026-06-04

Severity and scoring

CVSS: 5.3 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CWE: CWE-117

Affected products

Vendor	Product
morgan_project	morgan

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.

Source: NVD

References

[NVD]https://nvd.nist.gov/vuln/detail/CVE-2026-5078
[Other]https://cna.openjsf.org/security-advisories.html
[Vendor advisory]https://github.com/expressjs/morgan/security/advisories/GHSA-4vj7-5mj6-jm8m

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