CVE-2023-39507Network attack vector

Arbitrary website access via unrestricted URL scheme

Published Aug 16, 2023 · Updated Oct 8, 2024

Improper authorization in Rikunabi NEXT App for Android before 11.5.0 allows remote attackers to open arbitrary websites through the app. The custom URL scheme handler accepts intents from arbitrary apps and follows the supplied destination without restricting access to the URL-opening function. Exploitation requires user interaction with a malicious intent and can place an attacker-controlled phishing page in the app-mediated browsing flow.

CVSS severity4.3
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authorization in Rikunabi NEXT App for Android before 11.5.0 allows remote attackers to open arbitrary websites through the app. The custom URL scheme handler accepts intents from arbitrary apps and follows the supplied destination without restricting access to the URL-opening function. Exploitation requires user interaction with a malicious intent and can place an attacker-controlled phishing page in the app-mediated browsing flow.

The record

CVE
CVE-2023-39507
Published
Aug 16, 2023
Updated
Oct 8, 2024
Vendor
Recruit Co., Ltd.
Product
Rikunabi NEXT App for Android
Classifications
CWE-862, CWE-939, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 16, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 8, 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?

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

  1. Affected versionversion=prior to ver. 11.5.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Recruit Co., Ltd. · Rikunabi NEXT App for Androidversion=prior to ver. 11.5.0

Published CVSS scores

4.3JPCERT/CCAV:N/AC:M/Au:N/C:N/I:P/A:N
4.3JPCERT/CCCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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.

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-862Missing Authorization
CWE-939Improper Authorization in Handler for Custom URL Scheme
T1204.001Malicious Link

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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