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CVE-2026-10657— Out-of-bounds read in Zephyr DNS resolver mDNS suffix check (memcmp past string NUL)

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.

zephyrproject zephyr是zephyrproject组织开源的一款实时操作系统内核。 Zephyr 1.10.0版本至4.5.0之前版本存在缓冲区错误漏洞，该漏洞源于DNS解析器中的memcmp越界读取，当解析的主机名最终标签短于7字节时，读取超出字符串NUL终止符1-2字节，可能导致拒绝服务。

CVSS 3.7 · Low EPSS 0.29% · P21

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 1

VendorProduct Version RangeStatus
zephyrproject zephyr 1.10.0< 4.5.0 affected
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I. Basic Information for CVE-2026-10657

Vulnerability Information
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Vulnerability Title
Out-of-bounds read in Zephyr DNS resolver mDNS suffix check (memcmp past string NUL)
Source: CVE Program / CVE List V5
Vulnerability Description
Zephyr's DNS resolver detects mDNS (.local) queries in dns_resolve_name_internal() (subsys/net/lib/dns/resolve.c) with memcmp(strrchr(query, '.'), ".local", 7), which always reads a fixed 7 bytes from the suffix pointer. When the resolved hostname's final label is shorter than 7 bytes (e.g. names ending in .org, .com, .net, .io, or a trailing dot), the comparison reads 1-2 bytes past the string's NUL terminator. The hostname (query) is the caller-supplied name passed through the standard getaddrinfo()/dns_get_addr_info()/dns_resolve_name() path and is influenceable by operators or remote inputs (server names from configuration, parsed URLs, or app-facing interfaces). On a tightly-sized buffer with no slack (for example a userspace getaddrinfo call where the hostname is copied with k_usermode_string_alloc_copy to exactly strlen+1 bytes), the over-read crosses the allocation boundary; if that boundary is unmapped (guard page, memory-domain boundary under MPU, or an address sanitizer) the over-read faults, causing a denial of service. The over-read bytes are never returned, so there is no information disclosure. The flaw is compiled only when CONFIG_MDNS_RESOLVER is enabled, exists since v1.10.0, and is fixed by replacing the fixed-length memcmp with a NUL-safe strcmp(ptr, ".local").
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存读
Source: CVE Program / CVE List V5
Vulnerability Title
Zephyr 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
zephyrproject zephyr是zephyrproject组织开源的一款实时操作系统内核。 Zephyr 1.10.0版本至4.5.0之前版本存在缓冲区错误漏洞，该漏洞源于DNS解析器中的memcmp越界读取，当解析的主机名最终标签短于7字节时，读取超出字符串NUL终止符1-2字节，可能导致拒绝服务。
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 1.10.0 ~ 4.5.0 -

II. Public POCs for CVE-2026-10657

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III. Intelligence Information for CVE-2026-10657

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Patches & Fixes for CVE-2026-10657 (1)

Vendor Advisories for CVE-2026-10657 (1)

IV. Related Vulnerabilities

Same product: zephyr
Same vendor: zephyrproject
Same weakness: CWE-125

V. Comments for CVE-2026-10657

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