CVE-2021-27888Network attack vector

Stored XSS via crafted drop-off filenames

Published Mar 2, 2021 · Updated Aug 3, 2024

Cross-site scripting in ZendTo before 6.06-4 Beta allows remote attackers to execute browser script through a crafted drop-off filename. The flaw occurs when the drop-off display handles a stored filename containing unexpected characters; public sources do not identify the template or exact escaping operation. A recipient must view the affected drop-off, after which script runs in that viewer's browser context and can read or alter page-accessible data.

CVSS severity6.1
Medium
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in ZendTo before 6.06-4 Beta allows remote attackers to execute browser script through a crafted drop-off filename. The flaw occurs when the drop-off display handles a stored filename containing unexpected characters; public sources do not identify the template or exact escaping operation. A recipient must view the affected drop-off, after which script runs in that viewer's browser context and can read or alter page-accessible data.

The record

CVE
CVE-2021-27888
Published
Mar 2, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 2, 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 privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NVDCVSS:3.1/AV:N/AC:L/PR:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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

Public exploit references

No public exploit references are available in this record.

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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