CVE-2021-27558Public exploitNetwork attack vector

Script execution via data-link-creator attribute breakout

Published Aug 31, 2021 · Updated Aug 3, 2024

Cross-site scripting in EasyCorp ZenTao 12.5.3 allows remote attackers to execute arbitrary script through a crafted ZenTao link. The response places an attacker-controlled value in the data-link-creator attribute without safe output encoding, permitting attribute breakout and script injection. Execution requires a victim to open the crafted link; script then runs in that victim's ZenTao session and can issue same-origin requests with the victim's privileges.

CVSS severity6.1
Medium
EPSS probability0.84%
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 EasyCorp ZenTao 12.5.3 allows remote attackers to execute arbitrary script through a crafted ZenTao link. The response places an attacker-controlled value in the data-link-creator attribute without safe output encoding, permitting attribute breakout and script injection. Execution requires a victim to open the crafted link; script then runs in that victim's ZenTao session and can issue same-origin requests with the victim's privileges.

The record

CVE
CVE-2021-27558
Published
Aug 31, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 31, 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

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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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