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My Galaxy EUVDEUVD-2026-55100

| CVE-2026-21075 MEDIUM
Improper Authorization in Handler for Custom URL Scheme (CWE-939)
2026-08-10 SamsungMobile GHSA-grg8-xhr3-987r
5.3
CVSS 4.0 · Vendor: SamsungMobile
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Host malicious page with crafted URL scheme link
  2. Delivery
    Deliver link to Samsung Galaxy user via phishing or ad
  3. Exploit
    User taps link triggering My Galaxy URL handler
  4. Execution
    Handler processes request without authorization check
  5. Impact
    Sensitive information returned to attacker-controlled context

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V4 - API and Web Service Improper authorization in handler
Exploitation Conditions

My Galaxy (any version prior to 6.3) must be installed on the target Samsung Galaxy device. Exploitation requires passive user interaction (UI:P per the CVSS 4.0 vector) - specifically, the victim must click, tap, or otherwise trigger a link or redirect that invokes the My Galaxy custom URL scheme, such as via a malicious web page, phishing message, or rogue application. The attacker requires no account, no authentication, and no prior access to the device (PR:N, AV:N). Exploitation is limited to the information disclosure impact class (VC:L) with no integrity or availability consequence. Non-Samsung devices are not affected, as My Galaxy is a Samsung-exclusive application.

Impact

The CVSS 4.0 base score of 5.3 (Medium) reflects a network-reachable, low-complexity vulnerability requiring no attacker privileges but necessitating passive user interaction (UI:P), which is the primary friction point limiting mass exploitation. Confidentiality impact is low (VC:L) with no integrity or availability dimension. EPSS data was not provided in the intelligence feed, and no KEV listing exists, meaning widespread or automated exploitation has not been confirmed. The combination of PR:N and AV:N is notable - an attacker needs no account or foothold on the target - but UI:P means the victim must interact with attacker-controlled content. Real-world risk is therefore meaningful for targeted phishing or malicious advertisement scenarios against Samsung users, but low for opportunistic automated scanning. The absence of assigned CWE is a minor gap; affected version boundary (pre-6.3) is clearly stated by the vendor.

Exploit ScenarioDerived

An attacker creates a malicious web page or SMS/email message containing a crafted custom URL scheme link targeting the My Galaxy handler. When the Samsung device user taps or visits the link, the My Galaxy app processes the request without validating the caller's authorization, returning or exposing sensitive user information accessible to the attacker-controlled page. No public proof-of-concept exploit code has been identified at time of analysis.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 10, 2026

Improper authorization in the custom URL scheme handler of Samsung's My Galaxy app (all versions prior to 6.3) exposes sensitive information to remote attackers. The flaw exists because the handler processes inbound custom URL scheme invocations without enforcing adequate authorization checks, enabling an attacker-controlled web page or application to silently extract user data when a victim interacts with a crafted link. No public exploit code has been identified at time of analysis, and CISA KEV does not list this as actively exploited, but the zero-privilege requirement from the attacker's side and the broad Samsung device install base make timely patching advisable.

RemediationAI

Update My Galaxy to version 6.3 or later, which contains the authorization fix for the custom URL scheme handler. The patch is confirmed by Samsung Mobile via the August 2026 Samsung Mobile Security Bulletin at https://security.samsungmobile.com/serviceWeb.smsb?year=2026&month=08. Users should update through the Galaxy Store or system update mechanism on their Samsung device. As a compensating control prior to patching, users can avoid opening links from untrusted sources in browsers or messaging applications on affected devices, which reduces the likelihood of inadvertently triggering the vulnerable URL scheme handler. No configuration toggle to disable the custom URL scheme is documented in available data.

Affected VersionsENISA

My Galaxy patch: 6.3

Affects your stack

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Technical ContextAI · show details

Custom URL schemes (also called deep links) allow mobile applications to register a URI protocol handler - for example 'mygalaxy://' - so that external sources such as web browsers, SMS messages, or other apps can invoke specific in-app functionality. Proper authorization in such handlers requires that the app validate the caller's identity or intent before acting on the request or returning data. In My Galaxy prior to version 6.3, this validation is absent or insufficient, meaning any remote party that can induce user interaction with a crafted URL can invoke the handler and receive sensitive information in the response. The affected product is identified by CPE cpe:2.3:a:samsung_mobile:my_galaxy:*:*:*:*:*:*:*:* - a Samsung-exclusive companion application distributed on Galaxy devices. CWE classification was not assigned by the reporter, but the root cause is consistent with CWE-939 (Improper Authorization in Handler for Custom URL Scheme) or CWE-285 (Improper Authorization).

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (SamsungMobile) PRIMARY 5.3 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
vuln.today AI 4.3 MEDIUM

Network-reachable handler exploitable without attacker privileges, but requires victim to interact with a crafted link; only limited confidentiality impact, no integrity or availability effect.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (SamsungMobile).

CVSS VectorVendor: SamsungMobile

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
Passive
Vulnerable system: Confidentiality
Low
Vulnerable system: Integrity
None
Vulnerable system: Availability
None
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

DescriptionCVE.org

Improper authorization in handler for custom URL scheme in My Galaxy prior to version 6.3 allows remote attackers to access sensitive information.

Threat Intelligence Overview

EPSS Score
0.4%
Top 71% exploitable
Prevalence
Medium
Samsung-exclusive companion app, large but brand-scoped install base
Data Quality
4 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.4%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

26
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +26
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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