What happened

CISA added CVE-2025-21042 to the Known Exploited Vulnerabilities (KEV) catalog for Samsung mobile devices on 2025-11-10, with a remediation due date of 2025-12-01 per Binding Operational Directive guidance CISA KEV. The entry describes an out-of-bounds write in libimagecodec.quram.so that allows remote attackers to execute arbitrary code on affected devices CISA KEV. NVD lists the same CVE and confirms the vulnerability and impact scope for remote code execution NVD CVE-2025-21042. The CVE is categorized under CWE-787 (Out-of-bounds Write) in the public CVE record MITRE CVE record.

Bottom line: this vulnerability is confirmed exploited in the wild by virtue of its KEV inclusion CISA KEV.

Why it matters

An out-of-bounds write in a core image codec library is a high-impact primitive: image decoding runs frequently and often on untrusted content, turning a single parsing bug into code execution risk on a user’s primary communications device NVD CVE-2025-21042. Because this CVE is on the KEV, exploitation is not theoretical—CISA only lists vulnerabilities with evidence of active exploitation CISA KEV. The target surface—libimagecodec.quram.so—sits in the media pipeline on Samsung devices, so a successful exploit means arbitrary code execution in the context of the image processing stack CISA KEV.

For enterprise fleets with mixed BYOD/COPE footprints, this translates into potential device compromise, data exfiltration, and lateral movement from a consumer endpoint into corporate apps if device controls are lax NVD CVE-2025-21042.

Technical detail

CVE-2025-21042 is an out-of-bounds write (CWE-787) in Samsung’s libimagecodec.quram.so, which implies a write past allocated memory during image parsing MITRE CVE record. In practical terms, a crafted input processed by the image codec can corrupt adjacent memory structures, enabling control of instruction flow and arbitrary code execution on the device NVD CVE-2025-21042. The CISA KEV notes the impacted component path and explicitly flags the remote attacker execution outcome, confirming the risk profile and exploitation status CISA KEV.

Key points from the public records:

• Affected platform: Samsung mobile devices (mobile OS context) NVD CVE-2025-21042.
• Vulnerability class: Out-of-bounds write, CWE-787 MITRE CVE record.
• Impact: Remote code execution by a remote attacker NVD CVE-2025-21042.
• Exploitation status: Confirmed exploited; KEV inclusion CISA KEV.

While the public entries don’t enumerate a delivery vector, image codec bugs are typically triggered when the vulnerable library decodes untrusted image data, aligning with the RCE impact stated in the references NVD CVE-2025-21042. Operators should assume that any workflow which causes the device to decode images sourced from external parties can exercise the vulnerable path until patched CISA KEV.

Defense

Priority actions, aligned to the KEV entry and standard mobile fleet hygiene:

1) Patch and verify

• Apply vendor mitigations and updates as they are released; KEV entries require Federal Civilian Executive Branch agencies to remediate by the stated due date (2025-12-01) or remove the asset from service CISA KEV.
• Track CVE-2025-21042 across your asset inventory and verify closure by device model and OS build NVD CVE-2025-21042.

2) Reduce exposure pathways

• Until patched fleet-wide, minimize automatic handling of untrusted images in high-risk apps (where your MDM allows). This directly reduces the opportunity for remote RCE consistent with the vulnerability’s impact statement NVD CVE-2025-21042.

3) Monitor and respond

• Establish rapid response for devices exhibiting crashes or instability during media handling workflows; while not proof of exploitation, this is the operational surface where RCE would manifest per the CVE impact MITRE CVE record.
• Enforce least-privilege app permissions and restrict sideloading to limit post-exploitation blast radius, mindful that KEV-listed vulns reflect active attacker interest CISA KEV.

4) Governance

• For covered organizations, align remediation with Binding Operational Directive timelines noted in KEV or temporarily discontinue affected products where mitigations are unavailable CISA KEV.

Lyrie Verdict

Content-borne RCE in a core image codec is exactly the kind of fast, pre-interaction compromise that bypasses human-in-the-loop defenses. Lyrie’s stance is simple: treat media decoding as a hostile surface and instrument it for autonomous, machine-speed decisioning. In practice, that means two things for this CVE:

• Pre-execution content triage: score and gate untrusted image payloads before the device’s native decoder touches them, reducing opportunities for the vulnerable path to execute NVD CVE-2025-21042.
• Runtime anomaly enforcement: watch the media decoding pipeline for control-flow and memory integrity deviations characteristic of out-of-bounds writes (CWE-787), and cut execution when the pattern emerges—no wait for signatures, no analyst lag MITRE CVE record.

We map CVE-2025-21042 to Lyrie’s “untrusted media decode” threat family and ship autonomous controls that flag and stop abnormal decode paths tied to image codec libraries like libimagecodec.quram.so, aligning with the KEV’s active exploitation posture CISA KEV.