CVE-2018-1000855

easymon version 1.4 and earlier contains a Cross Site Scripting (XSS) vulnerability in Endpoint where monitoring is mounted that can result in Reflected XSS that affects Firefox. Can be used to steal cookies, depending on the cookie settings.. This attack appear to be exploitable via The victim must click on a crafted URL that contains the XSS payload. This vulnerability appears to have been fixed in 1.4.1 and later.

Published: 2018-12-20 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-1000855 is rated Moderate Risk (44.2/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.90%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2018-1000855

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.24% 0.90% +0.66%
2 2025-03-17 0.07% 0.24% +0.17%
3 2023-03-07 — 0.07% —

Full EPSS history (5 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-1000855

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 2.7 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2018-1000855

GitHub Security Advisory for CVE-2018-1000855

GHSA-c289-47qf-rvrr · Severity: medium · Ecosystem: rubygems — Cross Site Scripting (XSS) vulnerability in easymon

Affected software / configurations for CVE-2018-1000855

Vendor Product Version Raw CPE
basecamp easymon <= 1.4 cpe:2.3:a:basecamp:easymon:*:*:*:*:*:ruby:*:*

References for CVE-2018-1000855

URL Tags
https://github.com/basecamp/easymon/issues/26 Patch Third Party Advisory
https://github.com/basecamp/easymon/pull/25 Patch Third Party Advisory
cvelogic Threat Intelligence