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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 3 May 2022.
S\@t BrowserApplication · Trustedconnectivityalliance

CVE-2019-16256

CRITICAL · 9.8 CVSS v3.1 Published 2019-09-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
In the wild Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Some Samsung devices include the SIMalliance Toolbox Browser (aka S@T Browser) on the UICC, which might allow remote attackers to retrieve location and IMEI information, or retrieve other data or execute certain commands, via SIM Toolkit (STK) instructions in an SMS message, aka Simjacker.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The Simjacker vulnerability exists in the S@T Browser (SIMalliance Toolbox Browser) component running on the UICC (SIM card) in certain Samsung devices. Attackers exploit this by sending specially crafted SMS messages containing malicious SIM Toolkit (STK) instructions that can be executed by the S@T Browser, allowing remote extraction of location data, IMEI numbers, and potentially other device data or command execution.

MitigationMobile network operators should implement SMS filtering to block malicious STK instructions; users should rely on carrier-provided SIM updates or consider更换 to unaffected SIM cards, as this UICC-level vulnerability cannot be patched through standard device software updates.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
S\@t BrowserApplication
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify your device manufacturer
    Check your phone settings or physical device to confirm if it is a Samsung device
    Affected if The device is manufactured by Samsung, as this vulnerability affects certain Samsung devices with the S@T Browser on the SIM card
  2. Determine your mobile network operator
    Check your SIM card provider by looking at your phone's SIM status or the carrier name displayed on your device
    Affected if Your SIM card is provided by an operator that uses the S@T Browser firmware on their UICCs
  3. Verify if your SIM supports STK commands
    Access your phone's SIM card settings (Settings > Connections > SIM card manager or Settings > Network & Internet > SIM cards) and look for SIM toolkit or STK menu options
    Affected if Your SIM card has an active SIM Toolkit (STK) menu, which indicates the S@T Browser may be present and capable of executing STK commands received via SMS
  4. Contact your mobile carrier for vulnerability status
    Call your mobile network operator's customer support or visit a retail store to ask whether your SIM card uses the S@T Browser (SIMalliance Toolbox Browser) and if it is vulnerable to CVE-2019-16256
    Affected if Your carrier confirms that your SIM card contains the S@T Browser and has not applied mitigations to block malicious STK instructions
  5. Review carrier SMS filtering practices
    Ask your mobile network operator whether they have implemented SMS filtering to block malicious or unexpected STK instructions
    Affected if Your carrier has not implemented SMS filtering to block malicious STK commands

You are affected if your SIM card contains the S@T Browser firmware and your mobile carrier has not implemented SMS filtering to block malicious STK instructions sent via specially crafted SMS messages.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Mobile network operators should implement SMS filtering to block malicious STK instructions; users should rely on carrier-provided SIM updates or consider更换 to unaffected SIM cards, as this UICC-level vulnerability cannot be patched through standard device software updates.

Fix this in S\@t Browser Exploited in the wild — priority engagement
  • Consultation16.0 h
  • Implementation40.0 h
  • Testing24.0 h
  • Review / QA12.0 h
92.0 hours of engineering $16,160
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-16256 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data