CVE-2026-87859

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 67% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.3Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

morgan is an HTTP request logger middleware for Node.js. In versions before 1.12.1, its escapeLogField() function does not escape the double quote character, which delimits the quoted fields of the Apache combined log format that morgan emits. An unauthenticated remote attacker who controls a value written to a quoted field, such as the User-Agent or Referer header, can include a double quote to close that field early, so a log consumer that parses the log by field position reads attacker-supplied text as the following field. In the built-in formats this makes the recorded value differ from the value that was sent, and in custom formats that quote an attacker-controlled token before a server-controlled one it can forge values such as the response status. No newline is injected, so record separation stays intact. The issue is fixed in morgan 1.12.1, which escapes the double quote. Users should upgrade to morgan 1.12.1 or later.

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
39(Track)
EG Risk 39/100SSVC: Track

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
Severity53% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
33%
KEV
Not listed

Published

September 11, 2026

Last Modified

September 16, 2026

Advisory Details (2)

Auto-updated Sep 11, 2026
Patch available. Sources: github.
github Patch Available

morgan vulnerable to Log Injection via unescaped double quote in quoted log fields · Advisory · expressjs/morgan · GitHub

https://github.com/expressjs/morgan/security/advisories/GHSA-9f6g-j8ch-79g4
generic

Security Advisories | OpenJS Foundation CVE Numbering Authority

https://cna.openjsf.org/security-advisories.html

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 19× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-09-18 21:32 UTCEG score recompute
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-17 20:46 UTCEG score recompute
  4. 2026-09-17 19:32 UTCEPSS rescore
  5. 2026-09-16 18:07 UTCEG score recompute
  6. 2026-09-16 14:09 UTCEPSS rescore
  7. 2026-09-16 05:15 UTCEPSS rescore
  8. 2026-09-15 15:35 UTCEG score recompute
  9. 2026-09-15 03:12 UTCEPSS rescore
  10. 2026-09-14 14:44 UTCEG score recompute
  11. 2026-09-13 13:57 UTCEG score recompute
  12. 2026-09-12 13:11 UTCEG score recompute
  13. 2026-09-11 14:53 UTCEPSS rescore
  14. 2026-09-11 14:53 UTCEPSS rescore
  15. 2026-09-11 12:24 UTCEG score recompute
  16. 2026-09-11 11:45 UTCEG score recompute
  17. 2026-09-11 10:23 UTCEG score recompute
  18. 2026-09-11 09:25 UTCEG score recompute
  19. 2026-09-11 09:24 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-87859?
CVE-2026-87859 is a medium vulnerability published on September 11, 2026. morgan is an HTTP request logger middleware for Node.js. In versions before 1.12.1, its escapeLogField() function does not escape the double quote character, which delimits the quoted fields of the Apache combined log format that morgan emits. An unauthenticated remote attacker who controls a value…
When was CVE-2026-87859 disclosed?
CVE-2026-87859 was first published in the National Vulnerability Database on September 11, 2026, with the most recent update on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-87859 actively exploited?
CVE-2026-87859 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 66.7% of all scored CVEs.
What is the CVSS score of CVE-2026-87859?
CVE-2026-87859 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-87859?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-87859, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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