---
cve: "CVE-2026-15603"
severity: "MEDIUM"
cvss: 5.3
epss: "3.6%"
vendor: "morgan"
kev: false
exploited: false
published: "2026-08-28 16:17:07"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-02T19:03:01+02:00"
---

# CVE-2026-15603

> 5.3 MEDIUM · 🧪 PoC

## Beschreibung

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.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Gering | warn |
| A Verfügbarkeit | Keine | good |

## Schwachstellen-Klasse

- **CWE-117** — Improper Output Neutralization for Logs
  The product constructs a log message from external input, but it does not neutralize or incorrectly neutralizes special elements when the message is written to a log file.

## Angriffsmuster (CAPEC)

- [CAPEC-81 — Web Server Logs Tampering](https://capec.mitre.org/data/definitions/81.html) _(Severity: High)_
- [CAPEC-93 — Log Injection-Tampering-Forging](https://capec.mitre.org/data/definitions/93.html) _(Severity: High)_
- [CAPEC-268 — Audit Log Manipulation](https://capec.mitre.org/data/definitions/268.html)

## ATT&CK-Techniken

- [T1070 — Indicator Removal on Host](https://attack.mitre.org/techniques/T1070/)
- [T1562.002 — Impair Defenses: Disable Windows Event Logging](https://attack.mitre.org/techniques/T1562/002/)
- [T1562.003 — Impair Defenses: Impair Command History Logging](https://attack.mitre.org/techniques/T1562/003/)
- [T1562.008 — Impair Defenses: Disable Cloud Logs](https://attack.mitre.org/techniques/T1562/008/)

## Referenzen

- <https://github.com/expressjs/morgan/security/advisories/GHSA-jxfw-x594-9x9m>
- <https://cna.openjsf.org/security-advisories.html>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-15603) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_