CVE-2025-6533Public exploitNetwork attack vector

Unlimited password guessing via reusable CAPTCHA

Published Jun 24, 2025 · Updated Jun 25, 2025

Authentication bypass in xxyopen Novel-Plus 5.1.0 through 5.1.3 allows remote attackers to reuse a CAPTCHA for password guessing. The ajaxLogin method in novel-admin's LoginController compares the supplied CAPTCHA with the session value but never removes that value after a successful match. A remote attacker needs one valid CAPTCHA and its session, then can replay it across unlimited password guesses; account access still requires a correct password.

CVSS severity5.9
Medium
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in xxyopen Novel-Plus 5.1.0 through 5.1.3 allows remote attackers to reuse a CAPTCHA for password guessing. The ajaxLogin method in novel-admin's LoginController compares the supplied CAPTCHA with the session value but never removes that value after a successful match. A remote attacker needs one valid CAPTCHA and its session, then can replay it across unlimited password guesses; account access still requires a correct password.

The record

CVE
CVE-2025-6533
Published
Jun 24, 2025
Updated
Jun 25, 2025
Vendor
xxyopen
Product
Novel-Plus
Classifications
CWE-287, CWE-307, CWE-294, T1110
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 24, 2025CVE publishedPublication date reported by the CVE source.
  2. Jun 25, 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?

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

  1. Affected versionversion=5.1.0
  2. Affected versionversion=5.1.1
  3. Affected versionversion=5.1.2
  4. Affected versionversion=5.1.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

xxyopen · Novel-Plusversion=5.1.0; version=5.1.1; version=5.1.2; version=5.1.3

Published CVSS scores

5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
5.1VulDBAV:N/AC:H/Au:N/C:P/I:P/A:P
5.6VulDBCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
2.9VulDBCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

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-287Improper Authentication
CWE-307Improper Restriction of Excessive Authentication Attempts
CWE-294Authentication Bypass by Capture-replay
T1110Brute Force

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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