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Fencer Intel
medium 4.3

CVE-2026-103387 json

garycourt uri-js Mailto Header mailto.ts URI.parse uncaught exception

published last mo. modified last mo. also EUVD-2026-90361

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits
0
none known

Summary

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.

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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-2026-103387 updated cvss 4.3

uri-js: uri-js: Denial of Service via crafted mailto URI

  • Red Hat Hardened Images rust 1.98.1-1.hum1, jaeger 2.20.0-0.11.hum1, dotnet8.0 8.0.130-0.1.hum1, grafana13.1 13.1.6-0.5.hum1, grafana13.2 13.2.1-0.8.hum1, grafana12.4 12.4.10-0.10.hum1, +4 more
    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
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.32% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/garycourt/uri-js/issues/103 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:P/RL:X/RC:C
CNA 3.0 4.3 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:P/RL:X/RC:C
CNA 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P/E:POC/RL:ND/RC:C
CNA 4.0 2.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
CNA 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

  • garycourt uri-js

Classification

Weakness

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.