CVE-2024-31295Network attack vector

Unauthenticated CAPTCHA bypass via guessable challenge

Published May 17, 2024 · Updated Apr 28, 2026

Guessable CAPTCHA in BestWebSoft Captcha by BestWebSoft 5.2.0 and earlier allows remote attackers to bypass form verification. The CNA and referenced advisory do not disclose whether challenge generation, presentation, or answer validation makes the CAPTCHA guessable. No authentication or user interaction is required, and successful guesses defeat anti-automation checks on enabled forms without a reported confidentiality or availability impact.

CVSS severity5.3
Medium
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Guessable CAPTCHA in BestWebSoft Captcha by BestWebSoft 5.2.0 and earlier allows remote attackers to bypass form verification. The CNA and referenced advisory do not disclose whether challenge generation, presentation, or answer validation makes the CAPTCHA guessable. No authentication or user interaction is required, and successful guesses defeat anti-automation checks on enabled forms without a reported confidentiality or availability impact.

The record

CVE
CVE-2024-31295
Published
May 17, 2024
Updated
Apr 28, 2026
Vendor
BestWebSoft
Product
Captcha by BestWebSoft
Classifications
CWE-804, CAPEC-554, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 17, 2024CVE publishedPublication date reported by the CVE source.
  2. Apr 28, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a <=5.2.0 changes=[{"at":"5.2.1","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

BestWebSoft · Captcha by BestWebSoftversion=n/a <=5.2.0 changes=[{"at":"5.2.1","status":"unaffected"}]

Published CVSS scores

5.3PatchstackCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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-804Guessable CAPTCHA
CAPEC-554Functionality Bypass
T1190Exploit Public-Facing Application

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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