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CVE-2025-21043: Actively Exploited Zero-Day in Samsung Quram Image Codec

Published on
September 2025
CVE-2025-21043: Actively Exploited Zero-Day in Samsung Quram Image Codec
Table Of Contents
Introduction
Understanding CVE-2025-21043
Exploitation Details
Key Indicators to Watch (Quick IOC List)
Why This Matters
Historical Context / Similar CVEs
Mitigation and Protection
Conclusion
References
Samsung Quram Image Codec Vulnerability

Introduction

Imagine receiving a harmless-looking meme in a group chat. You don't even need to click "download"—the app automatically generates a preview. In that instant, your phone could be compromised. This is the reality of CVE-2025-21043, a critical zero-day vulnerability embedded in the core of millions of Samsung Galaxy devices. Exploited actively in the wild, it allows attackers to run arbitrary code via specially crafted images.

Rated CVSS 8.8 (High), this vulnerability has significant implications for both individual users and enterprise environments, as image processing occurs constantly across messaging apps, social media platforms, and browsers.

Understanding CVE-2025-21043

What is it?
  • Vulnerability type: Out-of-bounds write → Remote Code Execution (RCE).
  • Affected component: libimagecodec.quram.so — Samsung's proprietary Quram image codec library.
  • Affected devices: Samsung Galaxy devices running Android 13–16, prior to the September 2025 SMR Release 1.
  • CVSS v3.1 Score: 8.8 (High).
  • Exploitation status: Confirmed zero-day, observed in active attacks.
What is the Quram Codec?

The Quram image codec is a proprietary library developed by Samsung to handle decoding of various image formats. It offers optimized performance and compression compared to standard Android codecs and is deeply integrated into the system. It's used by Samsung apps (Gallery, Camera) and third-party apps that rely on system media APIs. Its privileged access and widespread integration make it a high-value target for attackers.

Exploitation Details

  • Attack vector: Remote (via network).
  • Privileges required: None.
  • User interaction: Minimal — exploitation may occur simply by receiving or previewing an image (zero-click scenario).
  • Impact: Complete compromise of the vulnerable process, potential persistence, data exfiltration, and lateral movement.

Attackers craft malicious images that trigger memory corruption when processed. The ubiquity of image previews in messaging apps (WhatsApp, Telegram, MMS) makes exploitation possible without the user opening the file.

Key Indicators to Watch (Quick IOC List)

File / Artifact Indicators
  • Recent image files in messaging, camera, and download folders (/sdcard/WhatsApp/Media/*, /sdcard/DCIM/*, /sdcard/Download/*).
  • Mismatched file header vs extension (e.g., .jpg file with invalid image header).
  • Images with appended non-image data or unusually large file size.
  • Suspicious files in app private storage (unexpected .dex, native libraries, or APKs).
  • Cached thumbnails matching suspect images.
Log Indicators
  • logcat entries: Fatal signal, SIGSEGV, or segfault referencing libimagecodec.quram.so.
  • Parser or decoder errors immediately preceding a crash.
  • Native crash dumps under /data/tombstones/.
  • App lifecycle anomalies: repeated restarts or ANR traces after opening images.
  • Kernel messages (dmesg) showing oops or denied actions around the same timestamp.
  • Network events immediately after image receipt (new outbound connections, DNS queries, unusual TLS SNI patterns).

Why This Matters

Supply Chain Impact:

This flaw is not limited to a single app; any application relying on Samsung's APIs or the standard Android MediaPlayer to display images can trigger the vulnerability. The Samsung Android ecosystem acts as a supply chain — a single vulnerability affects millions of devices worldwide.

Zero-Click Potential:

The flaw may be triggered simply by previewing a message in an app, without the user clicking anything. This zero-click capability is extremely valuable to attackers and dramatically increases the threat level.

Broader Cybersecurity Lessons:
  • Rapid patch management is non-negotiable.
  • Mobile visibility and centralized logging for managed devices are essential.
  • Ubiquitous components, even low-risk libraries, can become high-impact attack vectors.

Historical Context / Similar CVEs

  • CVE-2021-25350 — Samsung image decoder RCE via crafted HEIC image.
  • CVE-2020-8899 — Android media library OOB write, remote code execution.
  • CVE-2019-2215 — Android kernel use-after-free (illustrative of exploit chain impact).

These precedents show repeated targeting of media and codec libraries because they are widely used and often process externally supplied data.

Mitigation and Protection

For Users:
  • Update immediately to SMR Sep-2025 Release 1.
  • Verify patch level: Settings → About phone → Security patch level.
  • Avoid opening images from untrusted sources until patched.
For Enterprises:
  • Enforce patch rollout via Mobile Device Management (MDM).
  • Monitor for suspicious device behavior (unexpected crashes, app restarts, or unusual network traffic).
  • Consider sandboxing or re-encoding image attachments at the gateway for high-risk user groups.
  • Educate users about risks from unsolicited media files.

Conclusion

CVE-2025-21043 is a high-severity, actively exploited zero-day in Samsung's Quram image codec. Its zero-click potential and broad supply chain impact make prompt patching and focused hunting critical. Security teams should prioritize mobile patching, implement targeted detections for the indicators listed above, and treat mobile devices with the same urgency as servers and desktops.

References