CVE-2021-27368Public exploitNetwork attack vector

Stored XSS via executable contact-name templates

Published Feb 22, 2021 · Updated Aug 3, 2024

Stored XSS in MonicaHQ Monica 2.19.1's Contact page allows remote authenticated users to execute JavaScript in another user's browser. Contact name fields store Vue template expressions without neutralization, causing constructor payloads to run when a contact is viewed or edited. An account able to create or edit a contact can plant the payload; another user must open the contact, exposing data and actions available to the victim's session.

CVSS severity5.4
Medium
EPSS probability0.59%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in MonicaHQ Monica 2.19.1's Contact page allows remote authenticated users to execute JavaScript in another user's browser. Contact name fields store Vue template expressions without neutralization, causing constructor payloads to run when a contact is viewed or edited. An account able to create or edit a contact can plant the payload; another user must open the contact, exposing data and actions available to the victim's session.

The record

CVE
CVE-2021-27368
Published
Feb 22, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 22, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

3.5NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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