CVE-2025-21043

What it actually does

This vulnerability is an out-of-bounds write in Samsung's libimagecodec.quram.so image codec library before the SMR Sep-2025 Release 1 update. A crafted image or media file can cause the decoder to write memory outside the intended buffer, corrupting process memory and potentially allowing remote code execution in the context of the application or service that parses the content. Because image decoding can be triggered by messaging, gallery, browser, email, or preview workflows, exploitation may require little or no user interaction depending on the delivery path.

Why it matters to the business

Successful exploitation can allow an attacker to compromise affected Samsung mobile devices remotely, potentially leading to spyware deployment, data theft, account compromise, device surveillance, or broader operational disruption. The flaw is listed in CISA KEV and has active in-the-wild exploitation, with a CISA remediation due date of 2025-10-23, so organizations managing Samsung mobile fleets should treat remediation as urgent even though the EPSS score is currently modest.

How an attack unfolds

An attacker prepares a malformed image or media object designed to trigger memory corruption in libimagecodec.quram.so when the device attempts to decode it. The object is then delivered through a channel that causes image parsing, such as a messaging app, MMS/RCS, email attachment, browser content, social application, or file preview. When the vulnerable codec processes the content, the out-of-bounds write corrupts memory and may redirect execution to attacker-controlled code. If exploitation succeeds, the attacker gains code execution within the decoding process and may chain additional sandbox escape, privilege escalation, or persistence techniques to access sensitive data or maintain control of the device. Public reporting and KEV status indicate this vulnerability has been exploited in the wild.

How to fix it

Update affected Samsung devices to SMR Sep-2025 Release 1 or a later security maintenance release. If centralized mobile device management is available, enforce minimum patch levels and block or quarantine devices that remain below the September 2025 Samsung security update level. Where immediate patching is not possible, reduce exposure by disabling automatic media download and preview in messaging/email applications where configurable, restricting unknown senders, limiting use of high-risk messaging channels, and ensuring mobile threat defense controls are active. Mitigations are not a substitute for the vendor patch because the vulnerable library is part of the device software stack.

How to confirm the fix worked

Confirm that each managed Samsung device reports a Samsung security patch level corresponding to SMR Sep-2025 Release 1 or later. Validate through device settings, MDM inventory, EMM compliance reports, or Android device management APIs. For high-risk users, verify the installed firmware/build is vendor-approved and that libimagecodec.quram.so is from a patched system image. Attempted exposure can be assessed by checking whether devices process unsolicited media automatically, whether risky auto-download settings are enabled, and whether unpatched devices remain active in the fleet.

Typical attack path

1. Identify Samsung mobile devices that have not received SMR Sep-2025 Release 1 or a later security update.
2. Craft a malicious image or media file that triggers the out-of-bounds write in libimagecodec.quram.so.
3. Deliver the content through a remote channel that causes automatic or user-assisted parsing, such as messaging, email, browser, or app preview functionality.
4. Trigger vulnerable image decoding on the target device.
5. Achieve code execution in the affected application or media-processing context.
6. Optionally chain with additional exploits to escape sandboxing, escalate privileges, collect data, or deploy surveillance tooling.

How to detect it

Detection should focus on both exploitation attempts and post-exploitation activity. Review MDM/EMM inventory for devices below SMR Sep-2025 Release 1, then prioritize forensic triage of those devices. Useful sources include Android logcat captures, crash reports/tombstones, mobile threat defense alerts, EDR-for-mobile telemetry, messaging/email security logs, DNS/proxy logs, and application event logs around the time unsolicited media was received. Look for crashes in processes that load libimagecodec.quram.so, native crash tombstones showing SIGSEGV/SIGABRT or memory corruption during image parsing, and repeated crashes in messaging, gallery, browser, email, or media-provider components after receipt of image or media content. Because reliable public exploit payload indicators are not generally available, treat codec crashes on unpatched devices as suspicious when correlated with unknown senders, unusual attachments, or follow-on activity such as unknown app installs, accessibility-service abuse, unexpected VPN/profile installation, abnormal outbound connections, or elevated battery/network usage. If a device is suspected of compromise, preserve it for mobile forensic acquisition rather than wiping it immediately.

• libimagecodec.quram.so
• /system/lib64/libimagecodec.quram.so
• /system/lib/libimagecodec.quram.so
• SIGSEGV
• SIGABRT
• Out of bounds
• heap corruption
• Fatal signal 11
• Fatal signal 6
• tombstone
• media.codec
• mediaserver
• media.extractor
• com.samsung.android.messaging
• com.android.mms
• com.android.providers.media

What your security team should do

• Immediately inventory Samsung mobile devices and identify any below SMR Sep-2025 Release 1.
• Prioritize patching because the vulnerability is in CISA KEV and is reported as actively exploited in the wild.
• Enforce a minimum allowed Samsung security patch level through MDM/EMM compliance policy.
• Quarantine, restrict access, or increase monitoring for devices that cannot be updated by the 2025-10-23 KEV due date.
• Advise users, especially high-risk personnel, to avoid opening unexpected images, attachments, or media messages until patched.
• Disable automatic media download/preview in messaging and email applications where practical for unpatched devices.
• Review mobile threat defense, EDR for mobile, MDM, crash, and network telemetry for signs of exploitation or suspicious post-exploitation behavior.
• Escalate forensic review for any unpatched device showing media decoder crashes, unexpected app crashes after receiving media, unknown app installation, abnormal network beacons, or signs of spyware behavior.