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CVE-2026-8718— Out-of-bounds write in DTLS peer Connection ID getsockopt (`TLS_DTLS_PEER_CID_VALUE`) in Zephyr net sockets/TLS

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组织开源的一个面向物联网设备的实时操作系统。 zephyrproject zephyr 3.5.0版本至4.4.1之前版本存在缓冲区错误漏洞，该漏洞源于tls_opt_dtls_peer_connection_id_value_get()函数未验证缓冲区大小，将调用者提供的optval直接传递给mbedtls_ssl_get_peer_cid()，可能导致内核堆缓冲区溢出。

CVSS 8.4 · High EPSS 0.16% · P5

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 1

VendorProduct Version RangeStatus
zephyrproject zephyr 3.5.0< 4.4.1 affected
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I. Basic Information for CVE-2026-8718

Vulnerability Information
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Vulnerability Title
Out-of-bounds write in DTLS peer Connection ID getsockopt (`TLS_DTLS_PEER_CID_VALUE`) in Zephyr net sockets/TLS
Source: CVE Program / CVE List V5
Vulnerability Description
tls_opt_dtls_peer_connection_id_value_get() in subsys/net/lib/sockets/sockets_tls.c, which handles getsockopt(SOL_TLS, TLS_DTLS_PEER_CID_VALUE), passed the caller-supplied optval directly to mbedtls_ssl_get_peer_cid() without verifying the buffer was at least MBEDTLS_SSL_CID_OUT_LEN_MAX (default 32) bytes. mbedtls_ssl_get_peer_cid() copies the peer-negotiated DTLS Connection ID (length 1..MBEDTLS_SSL_CID_OUT_LEN_MAX) into that buffer without a destination-size parameter, so a caller-supplied optlen smaller than the CID causes a write of up to 31 bytes past the buffer end. In CONFIG_USERSPACE builds the getsockopt syscall verifier (z_vrfy_zsock_getsockopt) bounce-buffers the user's optval into a kernel allocation of exactly optlen bytes (k_usermode_alloc_from_copy -> z_thread_malloc), so an unprivileged user thread that passes a small optlen on a connected DTLS socket with Connection ID enabled induces a kernel-heap buffer overflow, with the overflowing content being the remote peer's CID. The defect requires CONFIG_MBEDTLS_SSL_DTLS_CONNECTION_ID, an established DTLS session with a negotiated peer CID, and (for the kernel-crossing case) CONFIG_USERSPACE. Introduced when the TLS_DTLS_CID option was added (v3.5.0). The fix rejects callers whose optlen is below MBEDTLS_SSL_CID_OUT_LEN_MAX with -EINVAL.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存写
Source: CVE Program / CVE List V5
Vulnerability Title
zephyrproject zephyr 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
zephyrproject zephyr是zephyrproject组织开源的一个面向物联网设备的实时操作系统。 zephyrproject zephyr 3.5.0版本至4.4.1之前版本存在缓冲区错误漏洞，该漏洞源于tls_opt_dtls_peer_connection_id_value_get()函数未验证缓冲区大小，将调用者提供的optval直接传递给mbedtls_ssl_get_peer_cid()，可能导致内核堆缓冲区溢出。
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 3.5.0 ~ 4.4.1 -

II. Public POCs for CVE-2026-8718

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III. Intelligence Information for CVE-2026-8718

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Patches & Fixes for CVE-2026-8718 (1)

Vendor Advisories for CVE-2026-8718 (1)

Same Patch Batch · zephyrproject · 2026-08-10 · 5 CVEs total

CVE-2026-11810 7.5 HIGH NULL-pointer dereference in UpdateHub OTA agent on empty inner metadata array (remote DoS)
CVE-2026-11809 3.7 LOW UpdateHub probe: uninitialized-heap out-of-bounds read of network-supplied metadata
CVE-2026-11811 3.7 LOW Socket file-descriptor leak in UpdateHub OTA client start_coap_client() leading to resourc
CVE-2026-11812 2.5 LOW UpdateHub: race condition on shared context causes out-of-bounds write and DoS

IV. Related Vulnerabilities

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

V. Comments for CVE-2026-8718

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