CVE-2026-15603

MEDIUMPre-NVD 5.35.3
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (20th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
5.3EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 5.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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 v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
39
EG Risk 39/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed (value × EchelonGraph’s weight)
Severity53% × 45%
The EG Score, 5.3 of 10.
Exploitation0.3% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.3%
EPSS %ILE
20th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 28, 2026

Last Modified

August 31, 2026

Advisory Details (2)

Auto-updated Aug 28, 2026
Patch available. Sources: github.
Web page

Security Advisories | OpenJS Foundation CVE Numbering Authority

https://cna.openjsf.org/security-advisories.html
GitHub advisoryMentions a patch (unverified)

morgan vulnerable to Log Forging via unescaped Unicode line separators · Advisory · expressjs/morgan · GitHub

https://github.com/expressjs/morgan/security/advisories/GHSA-jxfw-x594-9x9m

Vendor Advisories for CVE-2026-15603(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(4 across 4 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
node-morgan1.10.0+~1.9.3-1, 1.10.1+~1.9.10-1, 1.12.0+~1.9.10-1, 1.12.1+~1.9.10-1
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
node-morgan1.10.0+~1.9.3-1, 1.10.1+~1.9.10-1, 1.12.0+~1.9.10-1, 1.12.1+~1.9.10-1
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
node-morgan1.10.0+~1.9.3-1, 1.10.1+~1.9.10-1
  • every version up to 1.12.0+~1.9.10-1: fixed in 1.12.0+~1.9.10-1
—
npm(1)
PackageVulnerable rangeFix by version rangeDependents
morgan—
  • every version up to 1.12.0: fixed in 1.12.0
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 14× in last 7d / 48× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  2. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  3. 2026-10-12 16:31 UTCEG score recompute
  4. 2026-10-11 20:10 UTCEG score recompute
  5. 2026-10-11 17:22 UTCEG score recompute
  6. 2026-10-11 14:55 UTCEG score recompute
  7. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  8. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  9. 2026-10-10 03:50 UTCEG score recompute
  10. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  11. 2026-10-09 02:42 UTCEG score recompute
  12. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  13. 2026-10-08 00:53 UTCEG score recompute
  14. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  15. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  16. 2026-10-06 14:50 UTCEG score recompute
  17. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  18. 2026-10-05 14:35 UTCEG score recompute
  19. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  20. 2026-10-04 14:37 UTCEG score recompute
  21. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  22. 2026-10-03 14:18 UTCEG score recompute
  23. 2026-10-02 08:33 UTCEG score recompute
  24. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  25. 2026-10-01 08:35 UTCEG score recompute
Show 53 more
  1. 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  2. 2026-09-30 08:35 UTCEG score recompute
  3. 2026-09-29 15:20 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  4. 2026-09-29 08:36 UTCEG score recompute
  5. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  6. 2026-09-28 08:38 UTCEG score recompute
  7. 2026-09-27 13:47 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  8. 2026-09-27 08:40 UTCEG score recompute
  9. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  10. 2026-09-26 08:42 UTCEG score recompute
  11. 2026-09-25 00:12 UTCEG score recompute
  12. 2026-09-24 00:07 UTCEG score recompute
  13. 2026-09-23 00:09 UTCEG score recompute
  14. 2026-09-22 00:11 UTCEG score recompute
  15. 2026-09-21 00:11 UTCEG score recompute
  16. 2026-09-20 00:13 UTCEG score recompute
  17. 2026-09-19 00:14 UTCEG score recompute
  18. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  19. 2026-09-18 00:16 UTCEG score recompute
  20. 2026-09-17 00:18 UTCEG score recompute
  21. 2026-09-16 14:07 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  22. 2026-09-16 05:14 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  23. 2026-09-16 00:19 UTCEG score recompute
  24. 2026-09-14 00:22 UTCEG score recompute
  25. 2026-09-13 16:46 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  26. 2026-09-13 00:24 UTCEG score recompute
  27. 2026-09-12 15:00 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  28. 2026-09-12 00:25 UTCEG score recompute
  29. 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  30. 2026-09-11 09:36 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  31. 2026-09-11 00:27 UTCEG score recompute
  32. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  33. 2026-09-09 00:29 UTCEG score recompute
  34. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  35. 2026-09-07 20:28 UTCEG score recompute
  36. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  37. 2026-09-06 20:30 UTCEG score recompute
  38. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  39. 2026-09-05 20:31 UTCEG score recompute
  40. 2026-09-04 20:33 UTCEG score recompute
  41. 2026-09-02 20:24 UTCEG score recompute
  42. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  43. 2026-09-01 17:24 UTCEG score recompute
  44. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  45. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  46. 2026-08-30 20:19 UTCEG score recompute
  47. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  48. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  49. 2026-08-28 19:58 UTCEG score recompute
  50. 2026-08-28 19:44 UTCEG score recompute
  51. 2026-08-28 16:33 UTCEG score recompute
  52. 2026-08-28 15:29 UTCEG score recomputeFirst assessed: 5.3 MEDIUM
  53. 2026-08-28 15:25 UTCMITRE cvelistV5first tracked

Related CVEs(same product + same CWE)

Same product

3 shown

Debian:12:node-morgan · npm:morgan

Frequently asked(5)

What is CVE-2026-15603?
CVE-2026-15603 is a medium-severity vulnerability; its CVE record was published on August 28, 2026. 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…
When was the CVE record for CVE-2026-15603 published?
The CVE record for CVE-2026-15603 was published on August 28, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of August 31, 2026; the record at its source may have been updated since.
Is CVE-2026-15603 actively exploited?
CVE-2026-15603 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (20th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-15603?
CVE-2026-15603 has a CVSS base score of 5.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-15603?
A fix for CVE-2026-15603 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-15603 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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