CVE-2023-5554Network attack vector

Log interception via unverified TLS certificates

Published Oct 12, 2023 · Updated Dec 9, 2025

Improper certificate validation in LINE Client for iOS 13.12.0 through before 13.16.0 allows remote attackers to intercept financial-module logs via a man-in-the-middle position. The financial module transmits logs without verifying the TLS server certificate, allowing an attacker who can intercept the connection to impersonate the log server and read or alter transmitted data. Exploitation requires network interception; the vendor rates the issue medium severity, while NVD rates broader confidentiality, integrity, and availability impact as critical.

CVSS severity9.8
Critical
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in LINE Client for iOS 13.12.0 through before 13.16.0 allows remote attackers to intercept financial-module logs via a man-in-the-middle position. The financial module transmits logs without verifying the TLS server certificate, allowing an attacker who can intercept the connection to impersonate the log server and read or alter transmitted data. Exploitation requires network interception; the vendor rates the issue medium severity, while NVD rates broader confidentiality, integrity, and availability impact as critical.

The record

CVE
CVE-2023-5554
Published
Oct 12, 2023
Updated
Dec 9, 2025
Vendor
LINE Corporation
Product
LINE
Classifications
CWE-295, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 12, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 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?

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

  1. Affected versionversion=13.12.0 <13.16.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

LINE Corporation · LINEversion=13.12.0 <13.16.0

Published CVSS scores

4.8LINE CorporationCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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.

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-295Improper Certificate Validation
T1557Adversary-in-the-Middle

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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