CVE-2026-15603
MEDIUMDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 14% of all known CVEs.
References
Related Vulnerabilities
Other CWE-117 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2021-43410 | Medium | 5.3 | 2.4% | - | Fix |
| CVE-2022-32549 | Medium | 5.3 | 2.3% | - | - |
| CVE-2019-14864 | Medium | 6.5 | 1.9% | - | Fix |
| CVE-2021-42250 | Medium | 6.5 | 1.8% | - | Fix |
| CVE-2024-47083 | High | 7.5 | 1.6% | - | - |
| CVE-2020-25646 | High | 7.5 | 1.4% | - | - |
Common questions
How do I fix CVE-2026-15603?
No published fix for CVE-2026-15603 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-15603 being actively exploited?
Not that we know of. CVE-2026-15603 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.24% is the estimated probability that it will be exploited in the next 30 days. That is higher than 14% of all scored CVEs.
How severe is CVE-2026-15603?
CVE-2026-15603 has a CVSS v3 base score of 5.3, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
Embed a live status badge for CVE-2026-15603
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-28.