CVE-2026-33957 Overview
CVE-2026-33957 affects the CustOS Driver in the Samsung Mobile Processor Exynos 1580. The vulnerability allows a local attacker to request oversized shared memory from the custos_iwc device. This request triggers out-of-bounds read and write conditions in kernel memory. The flaw can lead to memory corruption or information leakage on affected devices.
The issue is classified under [CWE-787] (Out-of-bounds Write) and requires local access with low privileges. Samsung published details through its Semiconductor Product Security Updates portal.
Critical Impact
A local attacker interacting with the custos_iwc device can trigger out-of-bounds memory access in the Exynos 1580 CustOS driver, potentially corrupting kernel memory or leaking sensitive information.
Affected Products
- Samsung Mobile Processor Exynos 1580
- CustOS Driver component (custos_iwc device interface)
- Mobile devices integrating the Exynos 1580 SoC
Discovery Timeline
- 2026-09-14 - CVE-2026-33957 published to NVD
- 2026-09-14 - Last updated in NVD database
Technical Details for CVE-2026-33957
Vulnerability Analysis
The vulnerability resides in the CustOS Driver shipped with the Samsung Exynos 1580 mobile processor. The driver exposes the custos_iwc device to userspace for shared memory allocation between the operating system and the CustOS trusted environment. When a caller requests a shared memory region, the driver does not properly validate the requested size against allocated bounds.
An attacker with local access and low privileges can request an oversized shared memory allocation. The undersized backing buffer combined with the attacker-controlled size parameter permits reads and writes beyond the allocated region. This out-of-bounds access impacts kernel memory adjacent to the shared memory area.
The issue carries a scope change, meaning exploitation can affect resources beyond the vulnerable component itself. Confidentiality and availability are affected at a limited level, while integrity is not directly impacted according to the CVSS vector.
Root Cause
The root cause is missing or insufficient bounds validation when the CustOS Driver services shared memory requests through the custos_iwc device. The driver trusts the caller-supplied size parameter without enforcing an upper limit tied to the actual allocation. This maps to [CWE-787] Out-of-bounds Write and includes an out-of-bounds read primitive.
Attack Vector
Exploitation requires local access to the device and the ability to open and issue requests against the custos_iwc device node. High attack complexity indicates that specific conditions must be met, such as controlling memory layout or timing kernel allocations. No user interaction is required. Successful exploitation may leak kernel memory contents to userspace or corrupt kernel state, which can be leveraged for further privilege escalation in a multi-stage attack chain.
Refer to the Samsung CVE-2026-33957 Details advisory for vendor-provided technical information.
Detection Methods for CVE-2026-33957
Indicators of Compromise
- Unexpected processes opening or issuing ioctl calls against the custos_iwc device node on Exynos 1580 devices
- Kernel log entries indicating oversized shared memory allocation requests or memory access faults originating from the CustOS driver
- Unauthorized applications with local access attempting repeated allocation requests against CustOS interfaces
Detection Strategies
- Monitor kernel logs (dmesg, logcat) for CustOS driver warnings, oops messages, or KASAN reports referencing out-of-bounds access
- Audit application access to trusted execution environment device interfaces on mobile fleets
- Correlate crash reports and unexpected reboots on Exynos 1580 devices with process activity targeting the CustOS driver
Monitoring Recommendations
- Enable mobile device management telemetry to identify devices running vulnerable firmware revisions of the Exynos 1580 platform
- Track patch status across managed mobile devices using the Samsung Semiconductor security update portal as the authoritative source
- Alert on unsigned or side-loaded applications requesting access to low-level device nodes exposed by the CustOS driver
How to Mitigate CVE-2026-33957
Immediate Actions Required
- Apply the vendor security update for the Exynos 1580 CustOS Driver as soon as it is available through the device manufacturer
- Inventory mobile devices using the Exynos 1580 SoC and prioritize them for firmware update deployment
- Restrict installation of untrusted applications on affected devices until patches are deployed
Patch Information
Samsung publishes fixes for Exynos processor components through its semiconductor security update program. Review the Samsung Security Updates portal and the Samsung CVE-2026-33957 Details advisory for the specific patched firmware version. Coordinate with the mobile device OEM for delivery of the patched baseband or system image.
Workarounds
- Limit application installation to trusted sources such as vetted enterprise app catalogs to reduce local attack surface
- Enforce mobile device management policies that block sideloading and restrict access to low-level device interfaces
- Where feasible, remove or replace devices using the vulnerable Exynos 1580 platform in high-sensitivity deployments until patches are applied
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
