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Medium

net: TLS 1.2 connections allowed on TLS 1.3 sockets

Type: advisorySources: OSV

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.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-1677
Confirmed fixed CVEs
Not specified
Updated in this feed
4 Nov 2026, 16:34 UTC · Revision 1

Source evidence

net: TLS 1.2 connections allowed on TLS 1.3 sockets

core-osv · Original source

Published 11 May 2026, 05:52 UTC

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.

osv:CVE-2026-1677
Complete source record
{
  "id": "eab66cfd638232dfe2eb72696d111ed9e25f83f3b90ae1940069e00826887f27",
  "url": "https://osv.dev/vulnerability/CVE-2026-1677",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net: TLS 1.2 connections allowed on TLS 1.3 sockets",
    "summary": "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.",
    "evidence": "osv:CVE-2026-1677",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-1677",
      "aliases": [
        "CVE-2026-1677",
        "GHSA-23r2-m5wx-4rvq"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/zephyrproject-rtos/zephyr",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "684c9e8f32e4373a21098559f748f06915f950c9"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "*"
                      },
                      {
                        "fixed": "4.4.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v4.4.0-rc3",
            "v4.4.0-rc2",
            "v4.4.0-rc1",
            "v4.3.0",
            "v4.3.0-rc3",
            "v4.3.0-rc2",
            "v4.3.0-rc1",
            "v4.2.0",
            "v4.2.0-rc3",
            "v4.2.0-rc2",
            "v4.2.0-rc1",
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            "v4.0.0-rc2",
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            "v3.7.0",
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            "v3.7.0-rc2",
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            "v3.6.0-rc2",
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            "zephyr-v3.5.0",
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            "v3.5.0-rc3",
            "v3.5.0-rc2",
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            "zephyr-v3.4.0",
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            "v3.0.0",
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            "v3.0.0-rc2",
            "v3.0.0-rc1",
            "v2.7.99",
            "v2.7.0-rc3",
            "v2.7.0-rc2",
            "v2.7.0-rc1",
            "zephyr-v2.6.0",
            "v2.6.0",
            "v2.6.0-rc3",
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            "zephyr-v2.5.0",
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            "zephyr-v2.3.0",
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            "zephyr-v2.2.0",
            "v2.2.0",
            "v2.2.0-rc3",
            "v2.2.0-rc2",
            "v2.2.0-rc1",
            "v2.1.0-rc3",
            "v2.1.0-rc2",
            "v2.1.0-rc1",
            "zephyr-v2.0.0",
            "v2.0.0",
            "v2.0.0-rc3",
            "v2.0.0-rc2",
            "v2.0.0-rc1",
            "zephyr-v1.14.0",
            "v1.14.0",
            "v1.14.0-rc3",
            "v1.14.0-rc2",
            "v1.14.0-rc1",
            "zephyr-v1.13.0",
            "v1.13.0",
            "v1.13.0-rc3",
            "v1.13.0-rc2",
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            "zephyr-v1.12.0",
            "v1.12.0",
            "v1.12.0-rc3",
            "v1.12.0-rc2",
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            "zephyr-v1.11.0",
            "v1.11.0",
            "v1.11.0-rc3",
            "v1.11.0-rc2",
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            "zephyr-v1.10.0",
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            "zephyr-v1.9.0",
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            "v1.9.0-rc4",
            "v1.9.0-rc3",
            "v1.9.0-rc2",
            "v1.9.0-rc1",
            "v1.8.99",
            "zephyr-v1.5.0",
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            "v1.6.99",
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            "v1.5.0-rc2",
            "v1.5.0-rc1",
            "v1.5.0-rc0",
            "zephyr-v1.4.0",
            "v1.4.0",
            "v1.4.0-rc3",
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            "zephyr-v1.3.0",
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            "v1.1.0-rc1",
            "zephyr-v1.0.0",
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-1677.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:37.323869628Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/1xxx/CVE-2026-1677.json",
        "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-23r2-m5wx-4rvq",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-1677",
        "https://github.com/zephyrproject-rtos/zephyr"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-757"
        ],
        "cna_assigner": "zephyr",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/1xxx/CVE-2026-1677.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-1677",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 504752,
  "published_at": "2026-05-11T05:52:12.14+00:00"
}