CVE-2026-24091: Qualcomm C-v2x Buffer Overflow Vulnerability

CVE-2026-24091 Overview

CVE-2026-24091 is a memory corruption vulnerability affecting a broad range of Qualcomm chipsets and firmware. The flaw occurs when the bootloader's fastboot command handler processes improperly formatted input. An attacker with physical access and high privileges on a device in bootloader mode can trigger memory corruption, leading to potential code execution at the bootloader level. Qualcomm disclosed the issue in its June 2026 Security Bulletin, assigning it CWE-1286: Improper Validation of Syntactic Correctness of Input. The affected component is the fastboot protocol, used during early-boot device flashing and recovery operations.

Critical Impact
Successful exploitation can corrupt memory in the bootloader execution context, enabling secure boot bypass, persistent firmware compromise, or full device takeover before the operating system loads.

Affected Products

Qualcomm Snapdragon 8 Gen 1/2/3, Snapdragon 8 Elite, and Snapdragon 8 Elite Gen 5 mobile platforms
Qualcomm automotive platforms including SA8155P, SA8255P, SA8295P, SA8620P, SA8770P, and SA9000P
Qualcomm FastConnect, QCA, WCN, and WSA wireless and audio firmware lines
Qualcomm compute, IoT, XR, and modem-RF platforms (X1E80100, QCS series, Snapdragon X55/X65/X72/X75)

Discovery Timeline

2026-06-01 - CVE-2026-24091 published to NVD
2026-06-02 - Last updated in NVD database
June 2026 - Qualcomm publishes June 2026 Security Bulletin

Technical Details for CVE-2026-24091

Vulnerability Analysis

The vulnerability resides in the fastboot command parser inside the Qualcomm bootloader. fastboot is a low-level protocol used to flash partitions, unlock devices, and issue diagnostic commands over USB. When the parser receives a command containing improperly formatted input, it fails to validate syntactic correctness before passing the data to downstream memory operations. This results in memory corruption within the bootloader's execution context.

Because fastboot runs before the operating system and before most platform mitigations are active, corruption in this layer carries elevated risk. An attacker can influence control flow during a phase where Secure Boot, kernel hardening, and runtime protections are not yet enforced. The scope-changed nature of the flaw indicates that exploitation can affect components beyond the originally compromised execution context.

Root Cause

The root cause is classified as CWE-1286: Improper Validation of Syntactic Correctness of Input. The fastboot handler accepts input without verifying that command arguments conform to expected syntax, length, or delimiter structure. Malformed tokens cause downstream parsing routines to operate on out-of-spec data, corrupting adjacent memory.

Attack Vector

Exploitation requires physical access to the device and high privileges, typically meaning the device must be booted into fastboot mode with an unlocked or accessible bootloader interface. The attacker connects over USB and issues crafted fastboot commands containing malformed input. No user interaction is required once the device is in the vulnerable state. The vulnerability is not network-reachable and there are no public proof-of-concept exploits, exploit kits, or evidence of in-the-wild exploitation at the time of publication.

See the Qualcomm June 2026 Security Bulletin for vendor technical details.

Detection Methods for CVE-2026-24091

Indicators of Compromise

Unexpected device reboots into fastboot or EDL (Emergency Download) mode without administrative action
Bootloader status changes, including unlock state transitions or modified vbmeta partitions
Firmware versions or build fingerprints that do not match the approved gold image
USB connection logs showing prolonged fastboot sessions on production or fleet devices

Detection Strategies

Validate firmware integrity using attestation services and verified boot chain measurements at device check-in
Compare deployed bootloader and firmware versions against the Qualcomm June 2026 Security Bulletin baseline
Monitor mobile device management (MDM) telemetry for bootloader unlock events and verified boot state transitions

Monitoring Recommendations

Audit physical access to devices in regulated, kiosk, automotive, and IoT deployments where USB ports are exposed
Track and alert on devices entering fastboot mode outside scheduled maintenance windows
Maintain inventory of Qualcomm-based assets mapped to affected chipset SKUs for targeted patch tracking

How to Mitigate CVE-2026-24091

Immediate Actions Required

Apply OEM firmware updates that incorporate the Qualcomm June 2026 security patch as soon as they become available for each affected platform
Inventory all Qualcomm-based devices across mobile, automotive, IoT, and compute fleets to identify exposure
Restrict physical access to devices in shared, public, or unattended environments
Ensure bootloaders remain locked and verified boot is enforced on production devices

Patch Information

Qualcomm released fixes in its June 2026 Security Bulletin. Patches are delivered to device OEMs, who must integrate and distribute updates to end users through their standard firmware update channels. Refer to the Qualcomm June 2026 Security Bulletin for the complete list of affected components and patched versions. Customers should consult their OEM (handset vendor, automotive manufacturer, or IoT integrator) for device-specific update timelines.

Workarounds

Keep bootloaders locked and disable fastboot access where not operationally required
Use physical port-blocking controls or tamper-evident enclosures on high-value devices
Enforce device attestation policies through MDM to quarantine devices showing bootloader integrity failures
Disable or restrict USB debugging and developer options on production endpoints

bash

# Example: verify bootloader lock state and verified boot status on a connected Android device
adb shell getprop ro.boot.flash.locked
adb shell getprop ro.boot.verifiedbootstate
adb shell getprop ro.boot.vbmeta.device_state
# Expected secure values: 1, green, locked