A weakness has been identified in garycourt uri-js up to 4.4.1. This affects the function URI.parse of the file src/schemes/mailto.ts of the component Mailto Header Handler. This manipulation of the argument to causes uncaught exception. The attack may be initiated remotely. The exploit has been made available to the public and could be used for attacks. The project was informed of the problem early through an issue report but has not responded yet.
CVE-2026-103387
MEDIUMPre-NVD 4.34.3—Trending — 5 sources updated this weekElevated
EchelonGraph scoreHIGH confidence
Score 4.3 from GitHub Security Advisory (severity: LOW) published 2026-09-30. A secondary CVSS source baseline 4.3; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 4.3Exploit: Elevated riskExposed services: Not assessed
No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.
- CVSS v3
- 4.3
- EG Score
- 4.3MEDIUMhigh confidence
- EG Risk
- 35EG Risk 35/100CISA SSVC
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 computedSeverity43% × 45%Exploitation40% × 40%Automatability0% × 15%CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix. - EPSS PROB
- 0.3%
- EPSS %ILE
- 22nd
- KEV
- Not listed
CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).
No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table
Published
September 30, 2026
Last Modified
October 1, 2026
Advisory Details (2)
Auto-updated Sep 30, 2026No patch confirmed yet.
generic
GitHub - garycourt/uri-js: An RFC 3986 compliant, scheme extendable URI parsing/validating/normalizing/resolving library for JavaScript · GitHub
https://github.com/garycourt/uri-js/Vendor Advisories for CVE-2026-103387(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 15× in last 7d / 15× 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.
- 2026-10-03 19:53 UTCEG score recompute
- 2026-10-03 19:53 UTCGHSA enrichment
- 2026-10-03 14:25 UTCEPSS rescore
- 2026-10-02 22:00 UTCEG score recompute
- 2026-10-02 22:00 UTCGHSA enrichment
- 2026-10-02 00:07 UTCEG score recompute
- 2026-10-02 00:07 UTCGHSA enrichment
- 2026-10-01 19:49 UTCEPSS rescore
- 2026-10-01 02:13 UTCEG score recompute
- 2026-10-01 02:13 UTCGHSA enrichment
- 2026-09-30 20:22 UTCEG score recompute
- 2026-09-30 20:22 UTCNVD updateCVSS v4 → 2.1
- 2026-09-30 20:06 UTCEG score recompute
- 2026-09-30 19:51 UTCEG score recompute
- 2026-09-30 19:50 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-103387?
CVE-2026-103387 is a medium vulnerability published on September 30, 2026. A weakness has been identified in garycourt uri-js up to 4.4.1. This affects the function URI.parse of the file src/schemes/mailto.ts of the component Mailto Header Handler. This manipulation of the argument to causes uncaught exception. The attack may be initiated remotely. The exploit has been…
When was CVE-2026-103387 disclosed?
CVE-2026-103387 was first published on September 30, 2026, with the most recent update on October 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-103387 actively exploited?
CVE-2026-103387 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (22nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-103387?
CVE-2026-103387 has a CVSS base score of 4.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-103387?
No fix for CVE-2026-103387 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-103387 are linked in the Vendor Advisories panel on this page.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-103387
Is Your Infrastructure Affected by CVE-2026-103387?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.