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Medium

Acceptance of CertificateVerify Message before ClientKeyExchange in TLS 1.2

Type: advisorySources: OSV

In wolfSSL 5.8.2 and earlier, a logic flaw existed in the TLS 1.2 server state machine implementation. The server could incorrectly accept the CertificateVerify message before the ClientKeyExchange message had been received. This issue affects wolfSSL before 5.8.4 (wolfSSL 5.8.2 and earlier is vulnerable, 5.8.4 is not vulnerable). In 5.8.4 wolfSSL would detect the issue later in the handshake. 5.9.0 was further hardened to catch the issue earlier in the handshake.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-2645
Confirmed fixed CVEs
Not specified
Updated in this feed
4 Nov 2026, 15:41 UTC · Revision 1

Source evidence

Acceptance of CertificateVerify Message before ClientKeyExchange in TLS 1.2

core-osv · Original source

Published 19 Mar 2026, 17:10 UTC

In wolfSSL 5.8.2 and earlier, a logic flaw existed in the TLS 1.2 server state machine implementation. The server could incorrectly accept the CertificateVerify message before the ClientKeyExchange message had been received. This issue affects wolfSSL before 5.8.4 (wolfSSL 5.8.2 and earlier is vulnerable, 5.8.4 is not vulnerable). In 5.8.4 wolfSSL would detect the issue later in the handshake. 5.9.0 was further hardened to catch the issue earlier in the handshake.

osv:CVE-2026-2645
Complete source record
{
  "id": "216f950d8c9c17a79f5e95aeac309bbaed652004258196a12d59a575a3d14e5f",
  "url": "https://osv.dev/vulnerability/CVE-2026-2645",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Acceptance of CertificateVerify Message before ClientKeyExchange in TLS 1.2",
    "summary": "In wolfSSL 5.8.2 and earlier, a logic flaw existed in the TLS 1.2 server state machine implementation. The server could incorrectly accept the CertificateVerify message before the ClientKeyExchange message had been received. This issue affects wolfSSL before 5.8.4 (wolfSSL 5.8.2 and earlier is vulnerable, 5.8.4 is not vulnerable). In 5.8.4 wolfSSL would detect the issue later in the handshake. 5.9.0 was further hardened to catch the issue earlier in the handshake.",
    "evidence": "osv:CVE-2026-2645",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-2645",
      "aliases": [
        "CVE-2026-2645"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/wolfssl/wolfssl",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "59f4fa568615396fbf381b073b220d1e8d61e4c2"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "5.8.4"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "cpe": "cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "5.8.4"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v5.8.2-stable",
            "wolfEntropy1",
            "v5.8.0-stable",
            "v5.7.6-stable",
            "v5.7.4-stable",
            "v5.2.1",
            "v5.7.2-stable",
            "v5.7.0-stable",
            "v5.6.6-stable",
            "v5.6.4-stable",
            "WCv5.0-RC12",
            "WCv5.0-RC11",
            "WCv5.0-RC10",
            "v5.6.2-stable",
            "v5.6.3-stable",
            "v5.6.0-stable",
            "v5.5.4-stable",
            "v5.5.3-stable",
            "v5.5.2-stable",
            "v5.5.1-stable",
            "v5.5.0-stable",
            "v5.4.0-stable",
            "v5.3.0-stable",
            "v5.2.0-stable",
            "v5.1.0-stable",
            "v5.0.0-stable",
            "WCv5.0-RC9",
            "v4.8.0-stable",
            "v4.7.1r",
            "v4.7.0-stable",
            "v4.6.0-stable",
            "v4.5.0-stable",
            "v4.4.0-stable",
            "v4.3.0-stable",
            "v4.2.0c",
            "v4.2.0-stable",
            "v4.1.0-stable",
            "v4.0.0-stable",
            "list",
            "v3.15.7-stable",
            "v3.15.6",
            "v3.15.5a",
            "v3.15.5-stable",
            "WCv4-rng-stable",
            "v3.15.3-stable",
            "l",
            "v3.15.0-stable",
            "v3.14.4",
            "v3.14.2",
            "v3.14.0b",
            "v3.14.0a",
            "v3.14.0-stable",
            "v3.13.3",
            "v3.13.2",
            "v3.13.0-stable",
            "v3.12.2-stable",
            "v3.12.0-stable",
            "v3.11.1-tls13-beta",
            "v3.11.0-stable",
            "v3.10.3",
            "v3.10.2-stable",
            "v3.10.0a",
            "v3.10.0-stable",
            "v3.9.10b",
            "v3.9.10-stable",
            "v3.9.8",
            "v3.9.6w",
            "v3.9.6",
            "v3.9.1",
            "v3.9.0",
            "v3.8.0",
            "v3.7.3",
            "v3.7.1",
            "v3.7.0",
            "v3.6.9",
            "v3.6.8",
            "v3.4.6",
            "v3.4.2",
            "v3.4.0",
            "v3.3.3",
            "v3.3.0",
            "v3.2.6",
            "v3.2.4",
            "v3.2.0",
            "v2.9.4",
            "v2.9.2",
            "v2.9.1",
            "v0.5",
            "v2.9.0",
            "v2.8.6",
            "v2.8.5a",
            "v2.8.5",
            "v2.8.4",
            "v2.8.3",
            "v2.8.2",
            "v2.8.0",
            "v2.7.2",
            "v2.7.0",
            "v2.6.2",
            "v2.6.0",
            "v2.4.7",
            "v2.4.6",
            "v2.4.2",
            "v2.0.8",
            "v2.0.6",
            "v2.0.3",
            "v2.0.2",
            "v2.0rc3",
            "v2.0rc2b",
            "v2.0rc2",
            "v2.0rc1",
            "v1.9.0",
            "v1.8.8.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-2645.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:37.003530933Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/2xxx/CVE-2026-2645.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-2645",
        "https://github.com/wolfSSL/wolfssl/pull/9694"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-358"
        ],
        "cna_assigner": "wolfSSL",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/2xxx/CVE-2026-2645.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-2645",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 504213,
  "published_at": "2026-03-19T17:10:22.919+00:00"
}