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Actively exploited

CVE-2021-25489 Samsung Mobile Devices Improper Input Validation Vulnerability

Samsung mobile devices contain an improper input validation vulnerability within the modem interface driver that results in a format string bug leading to kernel panic.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch urgentlyCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 29 Jun 2023.
  • Rated Low severity (CVSS 3.3, scored by Vendor).
  • It has been in the catalogue for 1,226 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

Assuming radio permission is gained, missing input validation in modem interface driver prior to SMR Oct-2021 Release 1 results in format string bug leading to kernel panic.

Affected Versions

ProductVersions
Samsung Mobile Samsung Mobile DevicesO(8.1), P(9.0), Q(10.0), R(11.0) to before SMR Oct-2021 Release 1

From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for Samsung Mobile Devices. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply updates per vendor instructions or discontinue use of the product if updates are unavailable

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsCyber Essentials requires high and critical updates (CVSS 7.0 or above) within 14 days of release. Treat any exploited flaw the same way.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 20 Jul 2023 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

More Exploited Samsung Flaws

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CVE-2024-7399Samsung MagicINFO 9 Server Path Traversal VulnerabilityAdded 24 Apr 2026CVE-2025-21042Samsung Mobile Devices Out-of-Bounds Write VulnerabilityAdded 10 Nov 2025CVE-2025-21043Samsung Mobile Devices Out-of-Bounds Write VulnerabilityAdded 2 Oct 2025CVE-2025-4632Samsung MagicINFO 9 Server Path Traversal VulnerabilityAdded 22 May 2025CVE-2022-22265Samsung Mobile Devices Use-After-Free VulnerabilityAdded 18 Sep 2023CVE-2021-25487Samsung Mobile Devices Out-of-Bounds Read VulnerabilityAdded 29 Jun 2023

All 15 exploited Samsung vulnerabilities

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2021-25489
  3. CVE record: CVE-2021-25489
  4. FIRST EPSS
  5. security.samsungmobile.com/securityUpdate.smsb?year=2021&month=10