CVE-2026-1677

Zephyr sockets created with `IPPROTO_TLS_1_3` can still negotiate a TLS 1.2 connection when both TLS versions are enabled in Kconfig, because the socket-level protocol selection is not propagated to mbedTLS (e.g. via `mbedtls_ssl_conf_min_tls_version`). The ClientHello advertises both versions and the peer can establish TLS 1.2, so applications that assumed `IPPROTO_TLS_1_3` enforces TLS 1.3 may silently use TLS 1.2 and remain exposed to TLS 1.2-specific weaknesses. As a workaround, the `TLS_CIPHERSUITE_LIST` socket option can be restricted to TLS 1.3-only cipher suites.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-23r2-m5wx-4rvq	Exploit Patch Vendor Advisory Mitigation
https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-23r2-m5wx-4rvq	Exploit Patch Vendor Advisory Mitigation

Configurations

Configuration 1 (hide)

cpe:2.3:o:zephyrproject:zephyr:*:*:*:*:*:*:*:*

History

08 Jul 2026, 13:36

Type	Values Removed	Values Added
CWE		NVD-CWE-noinfo
References	~~() https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-23r2-m5wx-4rvq -~~	() https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-23r2-m5wx-4rvq - Exploit, Patch, Vendor Advisory, Mitigation
CPE		cpe:2.3:o:zephyrproject:zephyr::::::::
First Time		Zephyrproject zephyr Zephyrproject

11 May 2026, 18:16

Type	Values Removed	Values Added
References	~~() https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-23r2-m5wx-4rvq -~~	() https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-23r2-m5wx-4rvq -

11 May 2026, 06:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-05-11 06:16

Updated : 2026-07-08 13:36

NVD link : CVE-2026-1677

Mitre link : CVE-2026-1677

CVE.ORG link : CVE-2026-1677

JSON object : View

Products Affected

zephyrproject

zephyr

CWE

CWE-757

Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')

NVD-CWE-noinfo

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