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CVE-2026-12634— Out-of-bounds stack write in the settings NVS backend from over-reported nvs_read length

Quick assessment

Affected
zephyrproject zephyr
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Zephyr Project Zephyr是Zephyr Project组织开源的一款面向物联网设备的实时操作系统。 Zephyr Project Zephyr 2.0.0版本至4.5.0之前版本存在缓冲区错误漏洞，该漏洞源于NVS后端在读取设置名称条目时未对nvs_read()返回值进行限制，导致在固定74字节栈缓冲区越界写入单个NUL字节，可能造成崩溃或拒绝服务。

CVSS 5.3 · Medium EPSS 0.10% · P1

Possible ATT&CK Techniques 2 AI

T1044 T1142

Affected Version Matrix 1

VendorProduct Version RangeStatus
zephyrproject zephyr 2.0.0< 4.5.0 affected
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I. Basic Information for CVE-2026-12634

Vulnerability Information
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Vulnerability Title
Out-of-bounds stack write in the settings NVS backend from over-reported nvs_read length
Source: CVE Program / CVE List V5
Vulnerability Description
The NVS backend of the Zephyr settings subsystem (subsys/settings/src/settings_nvs.c) reads stored setting-name entries into fixed 74-byte stack buffers and NUL-terminates them with buf[rc] = '\0', where rc is the return value of nvs_read(). Per its contract, nvs_read() returns the full stored entry length (wlk_ate.len), which can exceed the supplied buffer length — only MIN(len, stored_len) bytes are actually copied, but the return value may be much larger, bounded only by the NVS sector size. Three sites (settings_nvs_cache_match(), settings_nvs_load(), and settings_nvs_save()) used this value directly as the NUL index without clamping, so an oversized stored name entry causes a single \0 byte to be written past the end of the stack buffer at an attacker-influenced offset (CWE-787). The oversized entry cannot arise through the normal settings API, where names are bounded by SETTINGS_MAX_NAME_LEN. It requires an actor able to write the flash that backs the settings partition — a co-resident or untrusted component sharing the flash device, a malicious settings image/restore, or offline/physical flash access (a shared-flash threat model). The malformed entry is parsed when settings_load() runs at boot or subsystem init, or during settings_save(). The out-of-bounds write is a single NUL byte at an offset equal to the crafted entry length (up to the NVS sector size), so the practical impact is a crash or denial of service and limited stack corruption rather than reliable code execution. There is no confidentiality impact, and the path is not reachable from the network through the ordinary settings interface. The fix skips any entry whose nvs_read() length is greater than or equal to the buffer size before performing the NUL store.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存写
Source: CVE Program / CVE List V5
Vulnerability Title
Zephyr Project Zephyr 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Zephyr Project Zephyr是Zephyr Project组织开源的一款面向物联网设备的实时操作系统。 Zephyr Project Zephyr 2.0.0版本至4.5.0之前版本存在缓冲区错误漏洞，该漏洞源于NVS后端在读取设置名称条目时未对nvs_read()返回值进行限制，导致在固定74字节栈缓冲区越界写入单个NUL字节，可能造成崩溃或拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
zephyrproject zephyr 2.0.0 ~ 4.5.0 -

II. Public POCs for CVE-2026-12634

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III. Intelligence Information for CVE-2026-12634

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Patches & Fixes for CVE-2026-12634 (1)

Vendor Advisories for CVE-2026-12634 (1)

Same Patch Batch · zephyrproject · 2026-08-19 · 3 CVEs total

CVE-2026-12522 8.8 HIGH Stack buffer overflow in Zephyr hl7800 modem driver parsing network-supplied +CGCONTRDP ad
CVE-2026-12633 8.1 HIGH Out-of-bounds write in IPv6 6LoWPAN Context Option handling via unauthenticated Router Adv

IV. Related Vulnerabilities

Same product: zephyr
Same vendor: zephyrproject
Same weakness: CWE-787

V. Comments for CVE-2026-12634

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