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Findings

CVE-2026-1677

Zephyr sockets created with can still negotiate a TLS 1.2 connection when both TLS versions are enabled in Kconfig, because the socket-level protocol selection is not…

Published May 11, 2026 · updated Oct 15, 2026 · zephyrproject zephyr

Zephyr sockets created with 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 ). The ClientHello advertises both versions and the peer can establish TLS 1.2, so applications that assumed enforces TLS 1.3 may silently use TLS 1.2 and remain exposed to TLS 1.2-specific weaknesses. As a workaround, the socket option can be restricted to TLS 1.3-only cipher suites.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. May 11, 2026 · NIST NVD

    Detected

    Zephyr sockets created with 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 ). The ClientHello advertises both versions and the peer can establish TLS 1.2, so applications that assumed enforces TLS 1.3 may silently use TLS 1.2 and remain exposed to TLS 1.2-specific weaknesses.

  2. Oct 15, 2026 · NIST NVD

    Updated

    Zephyr sockets created with 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 ). The ClientHello advertises both versions and the peer can establish TLS 1.2, so applications that assumed enforces TLS 1.3 may silently use TLS 1.2 and remain exposed to TLS 1.2-specific weaknesses.

Affected

  • cpe zephyrproject/zephyrversion unspecified

Sources

  • CVE.orgVulnerability recordCVE-2026-1677

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-2026-1677

    Zephyr sockets created with 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 ). The ClientHello advertises

    nvd.nist.gov

References