CVE-2021-27961Public exploitNetwork attack vector

Reflected XSS via unescaped action parameter

Published Jul 9, 2025 · Updated Jul 9, 2025

Reflected XSS in indexeva.php in EvaSys evesys 7.1 (2152) through 8.0 (2202) allows remote attackers to execute script via action. The endpoint reflects the action value into HTML without neutralizing quote and tag markup, allowing an injected image event handler to become executable content. The request requires no authentication; script execution is confined to the browser context that renders the crafted response.

CVSS severity6.5
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in indexeva.php in EvaSys evesys 7.1 (2152) through 8.0 (2202) allows remote attackers to execute script via action. The endpoint reflects the action value into HTML without neutralizing quote and tag markup, allowing an injected image event handler to become executable content. The request requires no authentication; script execution is confined to the browser context that renders the crafted response.

The record

CVE
CVE-2021-27961
Published
Jul 9, 2025
Updated
Jul 9, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 2025Record 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

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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.

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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 exploitPublished

Weakness, pattern, technique

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

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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