CVE-2026-21094: wpa_supplicant Buffer Overflow Vulnerability

CVE-2026-21094 Overview

CVE-2026-21094 is an improper input validation flaw in wpa_supplicant addressed in the Samsung Mobile Release (SMR) September 2026 Release 1. The vulnerability allows an adjacent network attacker to write memory outside allocated bounds. wpa_supplicant is the Wi-Fi client daemon responsible for WPA/WPA2/WPA3 key negotiation on Samsung mobile devices. Successful exploitation requires the attacker to be within radio range of the target device. Samsung documented the fix in its September 2026 security maintenance release.

Critical Impact
An adjacent attacker within Wi-Fi range can trigger an out-of-bounds write in wpa_supplicant, potentially corrupting memory used by the Wi-Fi supplicant process.

Affected Products

Samsung mobile devices running builds prior to SMR Sep-2026 Release 1
wpa_supplicant component as shipped by Samsung Mobile
Samsung Galaxy devices receiving the September 2026 security maintenance release

Discovery Timeline

2026-09-09 - CVE-2026-21094 published to the National Vulnerability Database
2026-09-10 - Last updated in NVD database
September 2026 - Samsung releases SMR Sep-2026 Release 1 containing the fix

Technical Details for CVE-2026-21094

Vulnerability Analysis

The vulnerability resides in Samsung's build of wpa_supplicant, the user-space daemon that handles Wi-Fi authentication and key exchange. Improper validation of untrusted input allows the process to write past the boundary of an allocated buffer. This class of defect is tracked as CWE-20 (Improper Input Validation) and typically results in adjacent memory corruption.

Because wpa_supplicant parses management frames and EAPOL messages from nearby access points and peers, malformed frames delivered over the air can reach the vulnerable code path. Out-of-bounds writes in a network-facing daemon can corrupt heap metadata, adjacent objects, or function pointers depending on allocator layout.

Root Cause

The defect stems from missing or insufficient length and range checks on attacker-controlled input processed by wpa_supplicant. Without proper bounds enforcement, a crafted field can cause the daemon to write bytes beyond the target buffer, satisfying the conditions for CWE-20 and an out-of-bounds write.

Attack Vector

Exploitation requires adjacent network access, meaning the attacker must be within Wi-Fi range of the victim device. No authentication is required, and no user interaction is needed. Samsung has not disclosed the specific frame or field responsible, and no public proof-of-concept exists. The attack complexity is high, reflecting the specific radio conditions and timing required to reach the vulnerable path.

See the Samsung Security Update September 2026 advisory for vendor details.

Detection Methods for CVE-2026-21094

Indicators of Compromise

Unexpected crashes, restarts, or tombstone files generated by the wpa_supplicant process
Repeated Wi-Fi disconnections or association failures near untrusted access points
Kernel or logcat entries showing SIGSEGV or SIGABRT signals delivered to wpa_supplicant

Detection Strategies

Monitor mobile device management (MDM) telemetry for Samsung devices running builds older than SMR Sep-2026 Release 1
Correlate Wi-Fi association anomalies with device location to identify potentially hostile access points
Review crash reports from enterprise mobile fleets for repeated failures in the Wi-Fi supplicant component

Monitoring Recommendations

Track patch level compliance for Samsung mobile endpoints against the September 2026 SMR baseline
Alert on devices connecting to unknown or rogue SSIDs in sensitive physical locations
Aggregate mobile crash telemetry into a centralized data lake for pattern analysis across the fleet

How to Mitigate CVE-2026-21094

Immediate Actions Required

Apply the Samsung SMR Sep-2026 Release 1 update to all affected Galaxy devices
Enforce minimum patch-level policies through your MDM or UEM platform
Restrict use of untrusted Wi-Fi networks for high-value users until devices are patched

Patch Information

Samsung addressed CVE-2026-21094 in SMR Sep-2026 Release 1. Details are published in the Samsung Security Update September 2026 bulletin. Users should install the September 2026 security maintenance release through the device's Software Update settings.

Workarounds

Disable Wi-Fi on unpatched devices when operating in untrusted physical environments
Prefer cellular data or corporate VPN tethering until the SMR update is applied
Configure MDM policies to whitelist known-good SSIDs and block auto-connection to open networks

bash

# Verify Samsung security patch level on a managed device
adb shell getprop ro.build.version.security_patch
# Expected value for remediation: 2026-09-01 or later