CVE-2025-51741Public exploitNetwork attack vector

Email bombing via reusable CAPTCHA cookie

Published Nov 25, 2025 · Updated Jul 5, 2026

Uncontrolled resource consumption in Echo Open-Source Community System 2.2 through 2.3 allows remote attackers to trigger email bombing. The password-reset endpoint accepts a client-supplied kaptcha value when it matches the client-controlled kaptchaOwner cookie, then dispatches mail for an arbitrary username. No authentication is required; repeated requests can consume server mail resources and flood downstream users with verification messages.

CVSS severity7.5
High
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in Echo Open-Source Community System 2.2 through 2.3 allows remote attackers to trigger email bombing. The password-reset endpoint accepts a client-supplied kaptcha value when it matches the client-controlled kaptchaOwner cookie, then dispatches mail for an arbitrary username. No authentication is required; repeated requests can consume server mail resources and flood downstream users with verification messages.

The record

CVE
CVE-2025-51741
Published
Nov 25, 2025
Updated
Jul 5, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 25, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 5, 2026Record 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

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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-400Uncontrolled Resource Consumption
T1499.003Application Exhaustion Flood

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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