CVE-2026-15603Network attack vectorHinoki check available

Log forging via unescaped Unicode line separators

Published Aug 28, 2026 · Updated Aug 28, 2026

Log forging in Express.js Morgan before 1.12.0 allows remote attackers to inject logical records through crafted HTTP request data. Morgan's token-escaping helper leaves U+0085, U+2028, and U+2029 intact when logging request URLs, headers, or Basic-auth usernames. No authentication or user interaction is required, but forged records appear only when downstream Unicode-aware processing treats those characters as line boundaries.

CVSS severity5.3
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Log forging in Express.js Morgan before 1.12.0 allows remote attackers to inject logical records through crafted HTTP request data. Morgan's token-escaping helper leaves U+0085, U+2028, and U+2029 intact when logging request URLs, headers, or Basic-auth usernames. No authentication or user interaction is required, but forged records appear only when downstream Unicode-aware processing treats those characters as line boundaries.

The record

CVE
CVE-2026-15603
Published
Aug 28, 2026
Updated
Aug 28, 2026
Vendor
body-parser
Product
Morgan
Classifications
CWE-117
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.12.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

body-parser · Morganversion=0 <1.12.0

Published CVSS scores

5.3GitHub Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-117Improper Output Neutralization for Logs

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo