TA critical zero-day vulnerability in Samsung smartphones, tracked as CVE-2025-21042, has been added to the CISA Known Exploited Vulnerabilities (KEV) catalog following reports of active exploitation by threat actors. This severe flaw allows attackers to execute arbitrary code remotely, granting them complete control of affected devices.
What Is CVE-2025-21042?
CVE-2025-21042 is an out-of-bounds write vulnerability located in the libimagecodec.quram.so library used by Samsung mobile devices. Classified under CWE-787, this type of bug occurs when software writes data outside the boundaries of allocated memory, leading to memory corruption and potential remote code execution (RCE).
What makes this vulnerability especially dangerous is that no user interaction is required. Attackers can remotely exploit the flaw to inject and run malicious code, steal sensitive data, or establish persistent backdoors on the device.
How Attackers Are Exploiting the Flaw
According to CISA, active exploitation campaigns are already targeting Samsung smartphones. While full details of these campaigns remain undisclosed, the exploitation likely involves maliciously crafted image files or media content that trigger the vulnerable library when processed by the device.
In real-world attacks, this could allow adversaries to:
- Deploy spyware or stalkerware
- Steal personal data, credentials, or messages
- Compromise enterprise networks through connected devices
- Install additional malware for persistence
Given Samsung’s global market share, the scale of potential exploitation is significant — making this a high-priority patching event.
CISA and Federal Directive
The Cybersecurity and Infrastructure Security Agency (CISA) added this flaw to its KEV catalog on November 10, 2025, officially confirming active exploitation in the wild.
Under Binding Operational Directive (BOD) 22-01, all U.S. federal agencies must patch or apply mitigations for this vulnerability by December 1, 2025.
This mandate underscores the seriousness of the threat and the urgency for public and private organizations alike to take immediate action.
Samsung’s Response and Related Vulnerabilities
Samsung has not yet released a detailed technical advisory for CVE-2025-21042, but prior patches indicate the company is addressing similar flaws.
In September 2025, Samsung fixed CVE-2025-21043, a related zero-day vulnerability in the same libimagecodec.quram.so library, hinting that attackers may be chaining similar bugs for wider compromise.
Security researchers recommend that users:
- Manually check for software updates in device settings
- Install the latest firmware and security patches
- Enable automatic updates for ongoing protection
How to Protect Your Samsung Device
To safeguard against CVE-2025-21042 and similar exploits:
- Update Immediately – Check Settings → Software Update → Download and Install on your Samsung device.
- Avoid Third-Party App Stores – Only install apps from Google Play or the Samsung Galaxy Store.
- Monitor Device Activity – Unusual battery drain, data usage, or overheating may signal compromise.
- Enable Play Protect and Device Encryption – Adds extra layers of defense.
- Use Mobile Security Solutions – Reputable antivirus or mobile endpoint protection can help detect exploit attempts.
Organizations managing large fleets of Samsung devices should implement Mobile Device Management (MDM) policies and network segmentation to reduce exposure.
Why This Vulnerability Matters
Zero-day vulnerabilities like CVE-2025-21042 highlight the evolving threat landscape for mobile devices. Smartphones are not just communication tools — they hold sensitive personal, financial, and corporate data, making them prime targets for cybercriminals and state-sponsored actors alike.
An RCE flaw that requires no user interaction and is actively exploited presents one of the most critical classes of vulnerabilities in mobile security today.
Key Takeaways
Users and enterprises: update or apply mitigations immediatelyy available patches without delay to safeguard personal and enterprise data.
CVE-2025-21042 affects Samsung mobile devices via libimagecodec.quram.so
Enables remote code execution without user action
Actively exploited — confirmed by CISA
Patch deadline for U.S. agencies: December 1, 2025
