Samsung Fixes Critical Zero-Day CVE-2025

CVE-2025-21043 is an out-of-bounds write vulnerability (CWE-787) in libimagecodec.quram.so, the image-decoding library used by Samsung Mobile Devices. It can be triggered remotely when the vulnerable codec processes maliciously crafted image data, and per the CVSS vector it requires no privileges or user interaction. A successful attack allows a remote attacker to execute arbitrary code on the device with high impact on confidentiality, integrity, and availability (CVSS 9.8, critical). All Samsung mobile devices running a security update prior to the September 2025 Maintenance Release (SMR Sep-2025 Release 1) are affected. The flaw is listed in CISA's Known Exploited Vulnerabilities catalog as of October 2, 2025, indicating exploitation in the wild, and headlines note Samsung patched it as an actively exploited zero-day; a related Samsung image-codec zero-day (CVE-2025-21042) was used to deliver LANDFALL spyware.

Do: Update affected Samsung devices to SMR Sep-2025 Release 1 or later via Settings > Software update, prioritizing devices exposed to untrusted image content (messaging, email, browsers). CISA KEV requires applying the vendor fix (or discontinuing use) under BOD 22-01 timelines for federal systems. Because exploitation has been observed in the wild and a related image-codec zero-day (CVE-2025-21042) was used to deploy LANDFALL spyware, verify fleet patch levels and investigate any devices showing signs of spyware infection.

CVE-2025-38352 is a time-of-check to time-of-use (TOCTOU) race condition (CWE-367) in the Linux kernel's POSIX CPU timers subsystem: when an exiting non-auto-reaping task has passed exit_notify() and handles CPU timers from interrupt context, it can be reaped by its parent or debugger right after unlock_task_sighand(), so a concurrent posix_cpu_timer_del() cannot detect that the timer is firing (cpu_timer_task_rcu() and/or lock_task_sighand() fail). A local attacker with low privileges who can manipulate POSIX CPU timers on such a task can win this race window, with high impact to confidentiality, integrity, and availability (CVSS 3.1: 7.8, local vector, no user interaction). Any system running an affected Linux kernel is exposed, including Debian GNU/Linux deployments and Android devices built on the kernel; practical reachability is limited where CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y routes timer handling through task work instead of IRQ context. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2025-09-04 and Google shipped it as an actively exploited fix in the September 2025 Android security update; EPSS currently estimates a 1.3% probability of exploitation within 30 days (68th percentile), and a public proof-of-concept is available.

Do: Apply updated kernel packages from your distribution (Debian and other vendors ship the upstream posix-cpu-timers fix) and install Google's September 2025 Android security patch on Android devices; CISA KEV listing requires federal agencies to apply vendor mitigations or discontinue use per BOD 22-01. Because exploitation requires local code execution, prioritize multi-tenant servers, build/CI hosts, and devices where untrusted users or apps run local code. A public proof-of-concept (github.com/farazsth98/chronomaly) is available for validation testing.

CVE-2025-48543 is a use-after-free (CWE-416) in the Android Runtime that exists in multiple code locations and allows an attacker who has already achieved code execution inside the Chrome sandbox to escape and attack the Android system_server process. The trigger requires only local access to the vulnerable component, with no additional execution privileges and no user interaction needed for exploitation. A successful attacker gains local escalation of privilege in the Android system server, making the bug especially useful as a privilege-escalation link in exploit chains against Android devices. Any Android device from Google's platform is in scope per CISA's listing (vendor: Google, product: Android, component: Android Runtime); specific affected version ranges are not enumerated in the source data. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2025-09-04 and Google's related headlines indicate it is being actively exploited in the wild; EPSS currently estimates only a 0.5% probability of exploitation in the next 30 days, and ransomware use is listed as unknown.

Do: Apply Google's Android security updates (September 2025 security bulletin patch level or later) as soon as they are available for your devices, since this flaw is listed in CISA's KEV and reported as exploited in the wild; per KEV required action, federal agencies must follow BOD 22-01 timelines or discontinue use if mitigations are unavailable. Use MDM/EDR tooling to verify device security patch levels, and note that because this is a sandbox-escape-to-system_server bug, it is most dangerous when chained with a browser/renderer exploit, so keeping Chrome/WebView current matters as well.