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Actively exploited

CVE-2025-21043 Samsung Mobile Devices Out-of-Bounds Write Vulnerability

Samsung mobile devices contain an out-of-bounds write vulnerability in libimagecodec.quram.so which allows remote attackers to execute arbitrary code.

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 2 Oct 2025.
  • Rated High severity (CVSS 8.8, scored by Vendor).
  • It has been in the catalogue for 400 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

Out-of-bounds write in libimagecodec.quram.so prior to SMR Sep-2025 Release 1 allows remote attackers to execute arbitrary code.

Affected Versions

ProductVersions
Samsung Mobile Samsung Mobile DevicesSee the vendor advisory

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 mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations 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 EssentialsRated high, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.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 23 Oct 2025 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-2025-4632Samsung 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 2023CVE-2021-25489Samsung Mobile Devices Improper Input Validation VulnerabilityAdded 29 Jun 2023

All 15 exploited Samsung vulnerabilities

Not Sure If You Are Exposed?

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2025-21043
  3. CVE record: CVE-2025-21043
  4. FIRST EPSS
  5. security.samsungmobile.com/securityUpdate.smsb?year=2025&month=09