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Samsung Flow EUVDEUVD-2026-97198

| CVE-2026-21134 MEDIUM
Improper Authentication (CWE-287)
2026-10-12 mobile.security@samsung.com GHSA-fm28-q8cf-g8mm
6.1
CVSS 4.0 · Vendor: samsung
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Attack ChainAIDerived

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

  1. Access
    Gain adjacent-network proximity to target
  2. Exploit
    Intercept Samsung Flow pairing handshake
  3. Execution
    Bypass improper authentication check
  4. Impact
    Access sensitive information over channel

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V6 - Authentication Authentication mechanism validation
MITRE ATT&CK

2 techniques across 2 tactics: Defense Evasion, Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires the attacker to be on an adjacent network (AV:A) - within Bluetooth, Wi-Fi Direct, or the same local wireless segment used by Samsung Flow to link a Galaxy phone with a paired PC or tablet - and to satisfy a specific attack requirement (AT:P in the 4.0 vector), implying exploitation is not reliably repeatable on demand and likely depends on timing or an in-progress pairing/connection state. No authentication or user interaction is needed (PR:N/UI:N). Limiting factors: the victim must be actively running Samsung Flow on a vulnerable build (< 4.9.22.4), the attacker must be in physical/network proximity, and the conditional attack requirement reduces the probability of a successful single attempt - all of which constrain realistic exploitation well below what the network-less CVSS base might suggest.

Impact

This is a moderate-severity information-disclosure flaw whose real-world risk is meaningfully constrained by its attack vector, not a drop-everything priority. The CVSS 4.0 vector (AV:A/AC:L/AT:P/PR:N/UI:N) confirms the attacker needs adjacent-network access (same Wi-Fi/Bluetooth/Wi-Fi Direct proximity) rather than remote internet reach, and the AT:P metric indicates a specific attack requirement must be met, which lowers automatability and mass-exploitation potential. On the impact side the vector claims high confidentiality (VC:H) with only low integrity/availability (VI:L/VA:L), consistent with the description's focus on accessing sensitive information. No EPSS score, no CISA KEV listing, and no public POC were provided in the intelligence, so there is no public exploit identified at time of analysis and no evidence of active exploitation - signals all point to a vendor-discovered, self-reported issue (reporter mobile.security@samsung.com) rather than an in-the-wild threat. One discrepancy to verify: the vendor vector asserts low integrity and availability impact, but the description mentions only information access (confidentiality), so the I/A impact ratings are not substantiated by the prose and should be confirmed with Samsung's bulletin. Net: patch in normal cycles; the adjacency requirement and absence of exploitation signals make this a managed-risk item rather than an emergency.

Exploit ScenarioDerived

An attacker within Bluetooth, Wi-Fi Direct, or shared local-network range of a victim running Samsung Flow abuses the improper authentication in the device pairing/connection handshake to impersonate or interpose on the trusted link between the phone and its paired PC or tablet. Having defeated the authentication check, the attacker reads sensitive data (such as notifications, clipboard, or transferred content) flowing over the Samsung Flow channel. No public exploit code was identified in the provided intelligence, and exploitation requires physical/network proximity to the target.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 12, 2026

Samsung Flow builds prior to 4.9.22.4 contain an improper authentication weakness that lets an attacker on an adjacent wireless network reach sensitive information exchanged or stored by the app. Exploitation is unauthenticated and requires no user interaction (CVSS 4.0 PR:N/UI:N), but the vector also requires a specific precondition (AT:P) and proximity, so a successful attempt depends on timing or an active pairing/connection state rather than being reliably repeatable on demand. Severity is moderate (6.1 base) and no public exploit code or confirmed active exploitation was identified at time of analysis; realistic risk is constrained by the adjacent-network vector and the conditional attack requirement.

RemediationAI

The primary fix is to upgrade Samsung Flow to version 4.9.22.4 or later on every paired device, using the vendor's release notes and the advisory at https://security.samsungmobile.com/serviceWeb.smsb?year=2026&month=10 to confirm availability per platform; because the link is two-sided, patch both the phone and the PC/tablet peer to fully close the channel. Where immediate upgrade is not possible, reduce exposure by disabling or signing out of Samsung Flow on devices that are regularly used in public or untrusted physical spaces, and turn off Bluetooth and Wi-Fi Direct when cross-device continuity is not needed - this defeats the AV:A vector but sacrifices the notification sync, handoff, and biometric-unlock features users rely on, and disabling Bluetooth may affect headsets, wearables, and peripherals. Enterprise environments can additionally restrict installation of Samsung Flow on managed corporate endpoints and keep paired personal devices off sensitive networks, accepting that this breaks the intended phone-to-PC workflow. There is no vendor-released patch alternative or version-independent workaround documented beyond upgrading to 4.9.22.4; the absence of a lower-impact configuration toggle means version upgrade remains the only complete remediation.

Affected VersionsENISA

Samsung Flow patch: 4.9.22.4

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Samsung Flow is Samsung's cross-device continuity service that links a Galaxy phone with a paired Windows PC or tablet over Bluetooth and Wi-Fi Direct to synchronize notifications, enable biometric unlock, and hand off content. The flaw is an authentication defect (CWE-287 class, mapped per the advisory as improper authentication) in the app's peer/connection handling: the service does not adequately verify the identity or authenticity of the adjacent party before granting access to sensitive data, allowing a co-located attacker who is on the same Bluetooth/Wi-Fi Direct segment to obtain information the peer link was intended to protect. The CVSS 4.0 vector (AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:L) and the independent assessment's CVSS 3.1 view (AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N) both agree the primary impact is high-confidentiality disclosure with no integrity or availability loss, that no credentials or user action are required (PR:N/UI:N), and that the attack is only reachable from an adjacent network. The AT:P / AC:H element reflects that exploitation hinges on a specific condition - most plausibly an in-progress pairing or active Flow session within radio range - which limits repeatability and makes the flaw far less exposed than a network-reachable issue of the same base score.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (samsung) PRIMARY 6.1 MEDIUM
CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:L/SC:N/SI:N/SA:N
vuln.today AI 5.3 MEDIUM

Adjacent proximity gives AV:A; the AT:P attack requirement maps to AC:H; no auth or interaction (PR:N/UI:N); description supports confidentiality only, so C:H with I:N/A:N.

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

Primary rating from Vendor (samsung).

CVSS VectorVendor: samsung

Attack Vector
Adjacent
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Vulnerable system: Confidentiality
High
Vulnerable system: Integrity
Low
Vulnerable system: Availability
Low
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

DescriptionCVE.org

Improper authentication in Samsung Flow prior to version 4.9.22.4 allows adjacent attackers to access sensitive information.

Threat Intelligence Overview

EPSS Score
0.2%
Top 92% exploitable
Prevalence
Medium
Samsung companion app common on Galaxy devices but not universally deployed
Social Media
1
Sightings
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 0.2%
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
Controlled
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

30
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +30
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

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