CVE-2026-21130

Executive Summary

CVE-2026-21130 is an improper input validation vulnerability in the CreditCardRetrieveActivity component of Samsung Checkout, Samsung's in-app payment processing framework. Local attackers on an affected device can leverage this flaw to launch an arbitrary activity using the elevated privileges granted to the Samsung Checkout application. The vulnerability affects Samsung Checkout versions prior to 5.1.03.1; no public proof-of-concept, exploit code, or Nuclei template is currently available, and the issue is not listed in CISA KEV.

Technical Analysis

The vulnerability class is CWE-20 (Improper Input Validation) mapped against an exported Android application component — specifically an Activity named CreditCardRetrieveActivity within the Samsung Checkout package. Android Activities declared in an application's manifest may be exposed to other applications on the same device when they are exported (either explicitly via android:exported="true" or implicitly through an intent-filter). If such an Activity performs insufficient validation on the incoming Intent — including the action, data URI, extras, or component targeting — a malicious local application can invoke it.

The concrete security consequence described by the NVD is that a local attacker can "launch an arbitrary activity with Samsung Checkout privileges." Samsung Checkout operates as a privileged payment application, so its process context carries permissions and trust relationships not ordinarily available to a third-party app. By abusing unvalidated input reaching CreditCardRetrieveActivity, an attacker can cause the Samsung Checkout process to start another Activity under its own identity, effectively borrowing those privileges.

Two mechanics are plausible given only the description, and both are consistent with improper input validation in an Activity entry point:

• Intent redirection / unsanitized nested Intent: the vulnerable Activity may read an Intent or Intent extra supplied by the caller and use it to start a downstream component without validating its target. The attacker thereby redirects an internal, privileged start into an attacker- or victim-controlled component.
• Unvalidated action/data handling: the Activity may select a target component or behavior based on caller-controlled data (action string, URI, or extra) without an allowlist, letting the caller dictate which component runs.

The precise parameter, extra key, or code path involved is not disclosed in the available CVE data, so no specific Intent keys, exported flags, or class internals can be asserted. No CVSS vector is published by NVD (score N/A), and no CWE mapping is included in the NVD record; the CWE-20 classification and the illustrative CVSS vector above reflect the stated vulnerability class and the "local" attack surface, not a vendor-published metric.

Because exploitation requires a malicious application already installed and running on the same device, this is a local privilege/trust-boundary issue rather than a remotely reachable network flaw. Exploitation does not require user interaction beyond the installation of the hostile app.

Exploitation Scenarios

No public PoC is available; the following chain is inferred strictly from the vulnerability class and the NVD description.

1. Reconnaissance / target identification: The attacker obtains a position to run code on the victim's Android device — typically by getting a malicious or trojanized app installed (sideloading, a repackaged app, or a compromised dependency). The attacker enumerates installed packages and identifies Samsung Checkout at a version prior to 5.1.03.1, and locates the exported CreditCardRetrieveActivity entry point.

2. Triggering the flaw: From the malicious app, the attacker constructs an Intent directed at the exposed CreditCardRetrieveActivity of Samsung Checkout and supplies the crafted input the Activity fails to validate (for example, a caller-controlled target or action). Because Samsung Checkout does not properly validate that input, the component accepts and acts on it.

3. Execution at the vulnerability-class level: The unvalidated input causes Samsung Checkout to start an arbitrary activity while running with its own privileges — i.e., intent redirection / unauthorized component launch executing in the Samsung Checkout security context. The attacker does not need a memory-corruption payload; the "payload" is the malformed or redirected Intent itself.

4. Post-exploitation impact: The launched activity executes with Samsung Checkout privileges, potentially exposing payment-related flows, leaking data accessible to that privileged process, or invoking functionality the attacker's own app could not reach directly. Integrity of the payment app's behavior can also be affected, since the attacker steers which component runs under its identity.

Note: Because the exact Intent parameters are undisclosed, the specific extras/actions required cannot be listed without fabrication.

Impact Assessment

• Confidentiality: Limited (C:L) — a launched activity may expose data reachable within the Samsung Checkout privilege domain.
• Integrity: Limited (I:L) — the attacker influences which component/activity executes under Samsung Checkout's identity.
• Availability: None (A:N) in the illustrative vector; the described issue does not imply service disruption.
• Attack Vector: Local (AV:L), requiring a hostile app on the device; no network reachability.
• Privileges Required: None (PR:N) beyond the ability to run a local app; User Interaction: None (UI:N) for the component launch itself.
• Scope: Unchanged (S:U) — impact stays within the Samsung Checkout security context.

Blast radius: Any Android device with Samsung Checkout < 5.1.03.1 installed. Impact is constrained to the device and the privileges of Samsung Checkout; there is no evidence of remote or cross-device exploitation. The primary business risk is abuse of a trusted payment application's privilege context by a co-resident malicious app, with possible exposure of payment-related data and unauthorized execution of privileged components. Because a precondition is a malicious local app, this is best treated as a defense-in-depth / trust-boundary concern rather than a mass-exploitation vector.

Detection Guidance

Sigma Rule

title: Suspicious Launch of Samsung Checkout CreditCardRetrieveActivity
id: 9f1c4b2a-7d3e-4a10-9b55-2c8e6f0a1d21
status: experimental
description: Detects a third-party app sending an Intent to Samsung Checkout's CreditCardRetrieveActivity, indicative of CVE-2026-21130 abuse.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-21130
author: Threat Intelligence
date: 2026/01/01
logsource:
  product: android
  service: activity_manager
detection:
  selection_component:
    event.action: 'am_proc_start'
    component|contains: 'CreditCardRetrieveActivity'
  selection_pkg:
    package|contains: 'com.samsung.android.samsungcheckout'
  filter_self:
    calling_package|contains: 'com.samsung.android.samsungcheckout'
  condition: selection_component and selection_pkg and not filter_self
fields:
  - calling_package
  - component
  - user_id
falsepositives:
  - Legitimate Samsung system components invoking checkout flows
level: medium
tags:
  - attack.t1626
  - cve.2026-21130

YARA Rule

rule Android_SamsungCheckout_CreditCardRetrieveActivity_CVE_2026_21130
{
    meta:
        description = "Flags Android apps referencing Samsung Checkout CreditCardRetrieveActivity for possible intent-redirection abuse (CVE-2026-21130)"
        author = "Threat Intelligence"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-21130"
        date = "2026-01-01"
        hash = "unknown"

    strings:
        $act = "CreditCardRetrieveActivity" ascii wide
        $pkg = "com.samsung.android.samsungcheckout" ascii wide

    condition:
        uint32(0) == 0x04034b50 and all of them
}

Suricata IDS Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-21130 Samsung Checkout CreditCardRetrieveActivity reference observed"; flow:established,to_server; content:"CreditCardRetrieveActivity"; http_client_body; nocase; threshold:type limit, track by_src, count 5, seconds 60; classtype:attempted-user; reference:cve,2026-21130; sid:2026211301; rev:1; metadata:affected_product Android, created_at 2026_01_01;)

Elastic Detection

process where event.type == "start" and
  process.name == "system_server" and
  process.args : "*CreditCardRetrieveActivity*" and
  not process.args : "*com.samsung.android.samsungcheckout*"

Splunk SPL Query

index=android sourcetype=logcat
| search "CreditCardRetrieveActivity" "com.samsung.android.samsungcheckout"
| rex field=_raw "from (?<calling_pkg>[a-zA-Z0-9_.]+)"
| where calling_pkg != "com.samsung.android.samsungcheckout"
| stats count min(_time) as first_seen max(_time) as last_seen by host calling_pkg
| where count > 0
| sort - count

Wazuh OSSEC Rule

<group name="android,cve_2026_21130,">
  <rule id="1001130" level="8">
    <decoded_as>android</decoded_as>
    <match>CreditCardRetrieveActivity</match>
    <regex>com\.samsung\.android\.samsungcheckout</regex>
    <description>CVE-2026-21130: Samsung Checkout CreditCardRetrieveActivity launched via external intent - possible privilege abuse</description>
    <mitre>
      <id>T1626</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source).

1. Immediate mitigations (no vendor patch evidence available):

   • Track device exposure: enumerate installed Samsung Checkout versions and flag any below 5.1.03.1.
   • Restrict installation of untrusted/sideloaded apps via MDM/EDM policy. The precondition for exploitation is a hostile local app; app-source control directly breaks the attack chain.
   • Where feasible, disable or de-privilege Samsung Checkout on devices that do not require it.

2. Patch / upgrade steps:

   • When available, update Samsung Checkout to version 5.1.03.1 or later via the vendor's official distribution channel (e.g., Galaxy Store / device update).
   • Re-verify the installed version after update; confirm no downgrade path is offered to the untrusted app.
   • Because no patch source is currently tracked, treat this as a known-unpatched condition and prioritize monitoring until a vendor build is confirmed.

3. Long-term hardening:

   • Require that exposed Android components validate all incoming Intents (action, data, extras, and target component) and reject external callers that are not allowlisted.
   • Prefer android:exported="false" for payment components and avoid forwarding caller-supplied Intents to internal component starts.
   • Maintain an inventory/patch-management process for privileged preinstalled payment apps and continuously monitor for advisory updates to Samsung Checkout.

References

• NVD — CVE-2026-21130: https://nvd.nist.gov/vuln/detail/CVE-2026-21130
• Samsung Mobile Security / Samsung Checkout vendor advisory portal: https://security.samsungmobile.com/
• CWE-20 Improper Input Validation: https://cwe.mitre.org/data/definitions/20.html
• MITRE ATT&CK T1626 — Abuse Elevation Control Mechanism: https://attack.mitre.org/techniques/T1626/
• Android developer guidance on exported components and Intent handling: https://developer.android.com/guide/topics/manifest/activity-element

Threat actor / exploit-in-the-wild evidence: None disclosed. CVE-2026-21130 is not listed in CISA KEV, no public PoC or exploit code has been identified, and no associated campaigns are reported in the available data.