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Fencer Intel
medium 5.3

CVE-2026-15603 json

morgan vulnerable to Log Forging via unescaped Unicode line separators

published 2mo ago modified 2mo ago also GHSA-jxfw-x594-9x9m , EUVD-2026-67720

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm morgan 1.12.0
  • morgan morgan 1.12.0
  • node-morgan Debian 14 1.12.0+~1.9.10-1

debian advisories DEBIAN-CVE-2026-15603

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-15603 updated cvss 5.3

morgan: morgan: Log Forging via unescaped Unicode line separators

  • Red Hat Cryostat 4 cryostat/cryostat-openshift-console-plugin-rhel9 Red Hat Enterprise Linux 9 npm, nodejs, sgx-mpa, tdx-qgs, sgx-libs, sgx-pccs, +6 more Red Hat Enterprise Linux 10 linux-sgx 2.26-7.el10, nodejs26 26.1.0-1.el10, nodejs22 22.23.1-3.el10_0, nodejs24 24.19.0-1.el10_2
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Fuse 7 morgan 1.6.1
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Hardened Images nodejs25 25.9.0-1.6.hum1, nodejs20 20.20.2-1.2.hum1
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Openshift Data Foundation 4 odf4/mcg-core-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images nodejs26 26.1.0-1.el10, nodejs22 22.23.1-3.el10_0, nodejs24 24.19.0-1.el10_2
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm morgan
<1.12.0
1.12.0

Affected products

  • morgan morgan

Classification

Weakness
  • CWE-117 Improper Output Neutralization for Logs

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.