CVE-2026-15603

morgan vulnerable to Log Forging via unescaped Unicode line separators

Published Aug 28, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
morgan is an HTTP request logger middleware for Node.js. In versions prior to 1.12.0, the internal helper that escapes log token values did not neutralize the Unicode line separator characters U+0085 (Next Line), U+2028 (Line Separator), and U+2029 (Paragraph Separator). An unauthenticated remote client can place these characters in an attacker-controlled log token, for example a Basic auth username surfaced through the remote-user token, so that Unicode-aware downstream log processing splits a single request log into multiple logical records. This is a log forging issue (CWE-117) and an incomplete-fix follow-up to CVE-2026-5078, which only addressed ASCII control characters. The issue is fixed in morgan 1.12.0, which extends the escaping set to cover these Unicode line separators. Upgrade to morgan 1.12.0 to remediate.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Github GHSA Github GHSA GHSA-jxfw-x594-9x9m morgan vulnerable to Log Forging via unescaped Unicode line separators
History
Type Values Removed Values Added
First Time appeared Morgan Project
Morgan Project morgan
CPEs cpe:2.3:a:morgan_project:morgan:*:*:*:*:*:node.js:*:*
Vendors & Products Morgan Project
Morgan Project morgan
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Morgan
Morgan morgan
Vendors & Products Morgan
Morgan morgan
Type Values Removed Values Added
Description morgan is an HTTP request logger middleware for Node.js. In versions prior to 1.12.0, the internal helper that escapes log token values did not neutralize the Unicode line separator characters U+0085 (Next Line), U+2028 (Line Separator), and U+2029 (Paragraph Separator). An unauthenticated remote client can place these characters in an attacker-controlled log token, for example a Basic auth username surfaced through the remote-user token, so that Unicode-aware downstream log processing splits a single request log into multiple logical records. This is a log forging issue (CWE-117) and an incomplete-fix follow-up to CVE-2026-5078, which only addressed ASCII control characters. The issue is fixed in morgan 1.12.0, which extends the escaping set to cover these Unicode line separators. Upgrade to morgan 1.12.0 to remediate.
Title morgan vulnerable to Log Forging via unescaped Unicode line separators
Weaknesses CWE-117
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
openjs
Published
Updated
Aug 28, 2026, 6:23 PM
Reserved
Jul 13, 2026, 3:00 PM
Status
Analyzed
Published
Aug 28, 2026, 4:17 PM
Modified
Aug 31, 2026, 5:11 PM
Severity
Moderate
Public date
Aug 28, 2026, 1:41 PM