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Samsung WSM Service EUVDEUVD-2026-97184

| CVE-2026-21120 HIGH
Use After Free (CWE-416)
2026-10-12 mobile.security@samsung.com GHSA-x3xp-pxrc-cvj6
8.9
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
    Install or compromise low-privilege app
  2. Delivery
    Issue crafted requests to WSM service
  3. Exploit
    Trigger use-after-free (win reuse race)
  4. Execution
    Reclaim freed memory with controlled data
  5. Impact
    Execute arbitrary code as system

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

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

Exploitation Conditions

Requires local code execution on the affected Samsung mobile device: the attacker must already run as some process (typically a malicious or compromised app) able to reach the WSM service interface - remote network exploitation is not possible (AV:L). Exploitation further depends on triggering and winning the use-after-free's timing/memory-reuse condition (reflected by AT:P), so success is probabilistic rather than guaranteed on a single attempt. No user interaction and no prior authentication or privilege are needed (PR:N/UI:N). The main limiting factors are the local-access prerequisite plus race reliability; the fix ships in SMR Oct-2026 Release 1, so patched devices are not affected.

Impact

This is a genuine high-priority local privilege-escalation/code-execution issue, but not a drop-everything internet-facing emergency. The CVSS 4.0 vector (AV:L/AC:L/AT:P/PR:N/UI:N) confirms it is locally exploitable by an unauthenticated process with no user interaction, and the impact metrics are maximal (VC:H/VI:H/VA:H plus subsequent-system SC:H/SI:H/SA:H), consistent with the description's claim of arbitrary code execution at system privilege. The AT:P (attack requirement present) value is the key nuance: a use-after-free typically must win a timing/memory-reuse condition, so reliable exploitation is not guaranteed on every attempt. No EPSS score, CISA KEV listing, or public POC was provided in the input, so there is no public exploit identified at time of analysis and no evidence of in-the-wild exploitation. The 8.9 score therefore reflects worst-case impact (full system compromise) rather than demonstrated exploitation, and the local-only vector means an attacker must already run code on the device. Conflict to verify: the input tags list 'Denial Of Service' alongside 'RCE', but the vendor-described outcome is code execution with system privilege - DoS is at most a degraded secondary outcome of the same memory-corruption bug, not a distinct capability.

Exploit ScenarioDerived

A malicious or compromised low-privilege app installed on a Samsung mobile device interacts with the WSM service in a way that triggers a use-after-free, then grooms the freed memory to hijack a dangling pointer. By winning the required timing/reuse condition, the attacker gains arbitrary code execution at system privilege, escaping the app sandbox. No public exploit code was identified in the provided data.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 12, 2026

Local privilege escalation in Samsung's WSM service lets a malicious or compromised process already running on the device trigger a use-after-free and execute arbitrary code with system-level privileges. The flaw affects Samsung mobile firmware builds released before SMR Oct-2026 Release 1; remote network exploitation is not possible because the attacker must first have local code execution able to reach the WSM interface. No public exploit code has been identified at time of analysis and there is no confirmed active exploitation (CISA KEV), but the cross-boundary impact (scope change with high confidentiality, integrity and availability impact) makes prompt installation of the October 2026 security maintenance release the priority for any unpatched device.

RemediationAI

Vendor-released patch: SMR Oct-2026 Release 1 - install the October 2026 Samsung security maintenance release (and any later SMR) on all affected devices, following the vendor bulletin at https://security.samsungmobile.com/securityUpdate.smsb?year=2026&month=10 to confirm per-model availability via OTA or Smart Switch. Because exploitation requires an attacker-controlled process already running on the device, compensating controls should focus on shrinking the local attack surface while patches roll out: block sideloading and restrict installation to vetted app stores (trade-off: breaks legitimate internal/enterprise APK distribution), enforce managed-device policies that limit which apps may run, and remove or sandbox untrusted applications on high-value devices. These measures reduce the likelihood that a hostile process ever reaches the WSM interface but do not remove the underlying memory-safety defect, so they are strictly interim; there is no network-side or configuration-only mitigation that eliminates the flaw.

Affected VersionsENISA

Samsung Mobile Devices patch: SMR Oct-2026 Release in Android 14, 15, 16, 17

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

The affected component is the WSM service shipped in Samsung mobile firmware, a system-level service exposed to on-device clients through the platform's IPC/service interface. The root cause is a use-after-free memory-safety defect (class CWE-416): a heap object associated with the service is freed while a stale reference remains reachable, so an attacker who can influence the free/reallocation timing can redirect execution through attacker-controlled memory. The CVSS 4.0 vector carries Attack Requirements: Present (AT:P), reflected in the independent assessment as AC:H, meaning exploitation depends on winning a memory-reuse/race window and is probabilistic rather than deterministic on a single attempt. The assessed vector (AV:L/PR:N/UI:N/S:C/C:H/I:H/A:H) confirms the practical constraints: no prior authentication or user interaction is needed (PR:N/UI:N), the attack is strictly local (AV:L), but a successful hit crosses a security boundary (S:C) because the WSM service operates with system privileges - turning an ordinary app-level foothold into system-level code execution. No CPE identifiers were provided, so component identification rests on the vendor bulletin rather than automated product mapping.

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Severity by source

Vendor (samsung) PRIMARY 8.9 HIGH
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
vuln.today AI 8.1 HIGH

Local vector (AV:L) by an unprivileged process (PR:N) with no interaction; AC:H reflects the use-after-free race, and gaining system privilege from a sandboxed context is a scope change (S:C) with full C/I/A impact.

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

Primary rating from Vendor (samsung).

CVSS VectorVendor: samsung

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

DescriptionCVE.org

Use after free in WSM service prior to SMR Oct-2026 Release 1 allows local attackers to potentially execute arbitrary code with system privilege.

Executive ViewAI

Why It Matters

Samsung mobile devices running firmware prior to the SMR Oct-2026 Release 1 contain a local privilege escalation flaw (CVE-2026-21120) in the WSM service that allows a compromised process to execute code with system-level privileges. This poses a significant risk to organizations with Samsung devices in their fleet, as a successful exploit could lead to full device compromise, data theft, and lateral movement. Leadership should prioritize patching once available and enforce interim mitigations to reduce the attack surface.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis; interim mitigations include enforcing least privilege, restricting local code execution, application whitelisting, disabling unnecessary services, and monitoring for anomalous WSM service activity.

Threat Intelligence Overview

EPSS Score
0.2%
Top 94% exploitable
Prevalence
High
WSM is a core service shipped across widely-deployed Samsung mobile devices
Social Media
1
Sightings
Data Quality
5 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 HIGH
CISA KEV No
Public POC No
EPSS 0.2%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Scheduled
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

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