Samsung Modem Interface Driver Out-of-Bounds Read Vulnerability (CVE-2021-25487)
Executive & SecOps Summary
SECOPS ASSESSMENTSamsung mobile devices and Exynos modem interface drivers prior to SMR Oct-2021 Release 1
Local attackers can execute arbitrary code with kernel privileges by dereferencing an invalid function pointer, leading to complete system compromise
Immediately apply the official Samsung Android security update (October 2021 or later)
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Enforce the latest firmware updates via Android Enterprise Mobile Management (EMM) or manual updates. Use the Android Debug Bridge (ADB) to verify the current security patch level.
# Check the security patch level of the connected Android device
adb shell getprop ro.build.version.security_patch
# Ensure the output date is 2021-10-01 or later.2. Temporary Workaround & Hardening Configuration
Since this is a kernel-level driver vulnerability, restrict the installation of untrusted applications until the patch is applied. Disable sideloading via MDM policies.
# Disable installation of apps from unknown sources via ADB
adb shell settings put global install_non_market_apps 03. Log Audit & IoC Verification Commands
Monitor system logs for abnormal kernel panics or crashes related to the modem interface driver.
# Filter logcat and dmesg for modem interface or set_skb_priv errors
adb logcat -d | grep -E -i 'set_skb_priv|modem|out-of-bounds'
adb shell dmesg | grep -E -i 'set_skb_priv|kernel_panic'Block Kernel Privilege Escalation & Ransomware Payloads Before You Can Reboot
Protect unpatched Windows, Linux, and macOS workloads against in-memory exploitation and lateral movement with autonomous EDR.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2021-25487) is an Out-of-Bounds (OOB) Read vulnerability caused by a lack of boundary checking of a buffer in the set_skb_priv() function of the Samsung modem interface driver. When processing private data of socket buffers (sk_buff), the driver fails to validate the input size, allowing references to memory locations outside the allocated buffer.
2. Exploitation Mechanics & Attack Scenario
A local attacker with basic execution privileges can send crafted system calls or IOCTL requests to the modem interface driver. Because set_skb_priv() lacks proper boundary checks, the driver reads beyond the intended buffer limits. By manipulating the adjacent memory layout, the attacker can trigger the dereference of an invalid function pointer, redirecting execution flow to arbitrary code within the kernel context.
3. Infrastructure & Business Impact
This vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation in the wild. When chained with local privilege escalation (LPE) techniques, it allows attackers to bypass application sandboxes, gain root privileges, exfiltrate sensitive user data, intercept communications, and establish persistent access on the device.
Official Vendor Advisories & References
Lack of boundary checking of a buffer in set_skb_priv() of modem interface driver prior to SMR Oct-2021 Release 1 allows OOB read and it results in arbitrary code execution by dereference of invalid function pointer.
Frequently Asked SecOps Questions (CVE-2021-25487)
FAQQ1. How critical is CVE-2021-25487 and is it actively exploited in the wild?
CVE-2021-25487 is rated CVSS 7.8 (HIGH) with a 30-day EPSS exploitation probability of 0.6%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2021-25487?
Primary impacted vendors include samsung across exynos, galaxy_firmware. Scope summary: Samsung mobile devices using firmware versions prior to the SMR Oct-2021 Release 1 (primarily Exynos-based models)
Q3. What temporary mitigations or workarounds exist for CVE-2021-25487 before patching?
[Mitigation] Immediately apply the official Samsung Android security update (October 2021 or later) Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2021-25487
Instantly format this advisory into an executive CISO summary or engineering patch ticket.
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