CVE-2026-3861

Repeated OS Dialog Trigger Causing Temporary iOS Device Inoperability via LINE In‑App Browser

Published Apr 16, 2026 CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed

Description

LINE client for iOS versions prior to 26.3.0 contains a vulnerability in the in-app browser where opening a crafted web page can repeatedly trigger OS-level dialogs due to insufficient safeguards when handling arbitrary URL schemes, potentially causing the iOS device to become temporarily inoperable.

Analysis

Technical impact

Opening a crafted web page in the LINE iOS in‑app browser repeatedly triggers OS‑level dialogs due to insufficient safeguards when handling arbitrary URL schemes, potentially causing the device to become temporarily inoperable. The flaw does not disclose data or execute code but causes a denial of service through repeated UI prompts, classified as an infinite‑loop type vulnerability (CWE‑451).

Affected Systems

The issue affects LINE client for iOS versions earlier than 26.3.0. Users running those versions are at risk if they encounter or click on links that load malicious content in the in‑app browser.

Risk and Exploitability

The CVSS score of 7.1 indicates high severity, and an EPSS score of < 1% indicates a low likelihood of exploitation. The vulnerability is not listed in the CISA KEV catalog, suggesting no widespread exploitation at this time. Exploitation requires user action – the victim must open the crafted page – making it a user‑interaction‑dependent denial of service.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

LY Corporation

LINE client for iOS

affected

Version	Status	Constraints
`26.3.0`	unaffected	< *

Configuration 1 [-]

cpe:2.3:a:linecorp:line:*:*:*:*:*:iphone_os:*:*

No data.

Vendor Product Versions

Line Corporation

Line Client For Ios

Version	Status	Scheme	Platform
`[0,26.3.0)`	affected	semver	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade the LINE iOS app to version 26.3.0 or later.
Avoid opening unknown or suspicious links in the LINE in‑app browser until the app is updated.
If an update is not immediately available, consider disabling the in‑app browser feature in the app settings or using an alternative messaging client.

Generated by OpenCVE AI on April 30, 2026 at 14:08 UTC.

Tracking

Advisories

No advisories available

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction Passive

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact Low

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.317% probability within 30 days)

Exploitation none

Automatable no

Technical Impact partial

References

Link	Providers
https://hackerone.com/reports/3422905

History

Apr 30, 2026 2:30 PM Title updated View changes

Type	Values Removed	Values Added
Title		Repeated OS Dialog Trigger Causing Temporary iOS Device Inoperability via LINE In‑App Browser

Apr 30, 2026 11:15 AM Description updated. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description	LINE client for iOS versions prior to 26.3.0 contains a vulnerability in the in-app browser where opening a crafted web page can repeatedly trigger OS-level dialogs, potentially causing the iOS device to become temporarily inoperable.	LINE client for iOS versions prior to 26.3.0 contains a vulnerability in the in-app browser where opening a crafted web page can repeatedly trigger OS-level dialogs due to insufficient safeguards when handling arbitrary URL schemes, potentially causing the iOS device to become temporarily inoperable.
Metrics		cvssV4_0 `{'score': 7.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L'}`

Apr 17, 2026 5:15 AM Title updated. Weaknesses updated View changes

Type	Values Removed	Values Added
Title	iOS Device Denial of Service via Repeated OS Dialogs in LINE In‑App Browser
Weaknesses	CWE-835

Apr 16, 2026 1:15 PM Weaknesses updated. Scoring metrics updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-451
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Apr 16, 2026 9:30 AM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Line Corporation Line Corporation line Client For Ios
Vendors & Products		Line Corporation Line Corporation line Client For Ios

Apr 16, 2026 9:15 AM Title updated. Weaknesses updated View changes

Type	Values Removed	Values Added
Title		iOS Device Denial of Service via Repeated OS Dialogs in LINE In‑App Browser
Weaknesses		CWE-835

Apr 16, 2026 6:30 AM Description updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		LINE client for iOS versions prior to 26.3.0 contains a vulnerability in the in-app browser where opening a crafted web page can repeatedly trigger OS-level dialogs, potentially causing the iOS device to become temporarily inoperable.
References		https://hackerone.com/reports/3422905
Metrics		cvssV3_1 `{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'}`