CVE-2026-1677 — Zephyr sockets created with `IPPROTO_TLS_1_3` can still

title: Zephyr IPPROTO_TLS_1_3 Socket Negotiating TLS 1.2 - CVE-2026-1677
id: scw-2026-05-11-ai-1
status: experimental
level: medium
description: |
  Detects Zephyr devices attempting to establish a TLS 1.2 connection when IPPROTO_TLS_1_3 was specified, indicating a potential exploitation of CVE-2026-1677. This allows attackers to leverage TLS 1.2 weaknesses on systems that should be enforcing TLS 1.3.
author: SCW Feed Engine (AI-generated)
date: 2026-05-11
references:
  - https://shimiscyberworld.com/posts/nvd-CVE-2026-1677/
tags:
  - attack.initial_access
  - attack.t1190
logsource:
    category: proxy
detection:
  selection:
      dst_port:
          - '443'
      cs-uri-query|contains:
          - 'TLS 1.2'
      condition: selection
falsepositives:
  - Legitimate administrative activity

Source: Shimi's Cyber World · License & reuse