CVE-2026-12522

Crash or code execution via unbounded address copies

Published Aug 19, 2026 · Updated Aug 20, 2026

Stack buffer overflow in the HL7800 modem driver in Zephyr RTOS before 4.4.2 allows adjacent attackers to crash devices via crafted +CGCONTRDP responses. In on_cmd_atcmdinfo_ipaddr() in drivers/modem/vendor_standalone/hl7800.c, delimiter-derived field lengths from network-supplied PDP parameters are passed directly to strncpy() for temp_addr_str and dns_v4_string without checking the fixed destination sizes. Exposure requires a malicious or impersonated cellular network, such as a rogue base station, and reaches the modem worker thread in supervisor context during normal attach, with crash as the minimum proven outcome and control-flow hijacking possible on targets without stack protection.

CVSS severity8.8
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack buffer overflow in the HL7800 modem driver in Zephyr RTOS before 4.4.2 allows adjacent attackers to crash devices via crafted +CGCONTRDP responses. In on_cmd_atcmdinfo_ipaddr() in drivers/modem/vendor_standalone/hl7800.c, delimiter-derived field lengths from network-supplied PDP parameters are passed directly to strncpy() for temp_addr_str and dns_v4_string without checking the fixed destination sizes. Exposure requires a malicious or impersonated cellular network, such as a rogue base station, and reaches the modem worker thread in supervisor context during normal attach, with crash as the minimum proven outcome and control-flow hijacking possible on targets without stack protection.

The record

CVE
CVE-2026-12522
Published
Aug 19, 2026
Updated
Aug 20, 2026
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-787
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.4.0 <4.4.2

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Zephyr Project · Zephyr RTOSversion=2.4.0 <4.4.2

Published CVSS scores

8.8Zephyr ProjectCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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