CVE-2026-12522

Received Received - Intake

Buffer Overflow in HL7800 Cellular Modem Driver

Publication date: 2026-08-19

Last updated on: 2026-08-19

Assigner: Zephyr Project

Description

The HL7800 cellular modem driver's +CGCONTRDP: response handler on_cmd_atcmdinfo_ipaddr() in drivers/modem/vendor_standalone/hl7800.c parses the PDP-context dynamic parameters (local address, subnet mask, gateway, and DNS servers) that the cellular network assigns to the device. The response is linearized into a 256-byte stack buffer, after which each address field length is computed from comma/. delimiter positions in the network-supplied data and used directly as the length argument to strncpy() into the fixed 64-byte stack buffer temp_addr_str (and the 16-byte iface_ctx.dns_v4_string). Because the field length is derived from attacker-controlled delimiter positions and was not bounded against the destination buffer, a single field can be far larger than 64 bytes. A malicious or impersonated cellular network (for example a rogue base station) can return a crafted +CGCONTRDP response with an overlong address field, causing strncpy() to write past temp_addr_str on the modem worker thread's stack, plus an out-of-bounds NUL write at temp_addr_str[addr_len]. No device-side privileges or user interaction are required: the device itself issues the AT+CGCONTRDP=1 query during normal network attach and parses whatever the network returns. The overflow corrupts adjacent stack memory in supervisor context, yielding at minimum a remotely triggerable crash and potentially control-flow hijacking on targets without stack protection. The fix bounds every field length against its destination buffer (temp_addr_str and dns_v4_string) before each copy, rejecting overlong fields.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-19

Last Modified

2026-08-19

Generated

2026-08-20

AI Q&A

2026-08-20

EPSS Evaluated

N/A

NVD

CVE-2026-12522

Affected Vendors & Products

Vendor	Product	Version / Range
zephyrproject	hl7800	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-787	The product writes data past the end, or before the beginning, of the intended buffer.

Attack-Flow Graph

Executive Summary

This vulnerability involves a buffer overflow in the HL7800 cellular modem driver. The driver parses network-assigned IP address details into a fixed-size stack buffer without proper length validation. An attacker-controlled cellular network can send a maliciously crafted response with an overly long address field, causing the driver to write beyond the buffer and corrupt adjacent stack memory. This can lead to crashes or potential remote code execution.

Detection Guidance

Detection requires monitoring for crashes or unusual behavior in devices using the HL7800 modem driver. Check modem logs for +CGCONTRDP response parsing errors or stack corruption. No specific commands are provided in the context.

Impact Analysis

If exploited, this vulnerability could allow a remote attacker to crash the device or take control of it by sending a malicious network response. Since the device automatically queries the network during normal operation, no user interaction is needed. This could disrupt device functionality or enable further attacks on connected systems.

Mitigation Strategies

Apply the vendor-provided patch that bounds field lengths before copying. Disable automatic +CGCONTRDP queries if possible or isolate devices from untrusted networks until patched. Monitor for crashes or unexpected behavior.

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