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wolfssl — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2023-6937

wolfSSL prior to 5.6.6 did not check that messages in one (D)TLS record do not span key boundaries. As a result, it was possible to combine (D)TLS messages using different keys into one (D)TLS record. The most extreme edge case is that, in (D)TLS 1.3, it was possible that an unencrypted (D)TLS 1.3 record from the server containing first a ServerHello message and then the rest of the first server flight would be accepted by a wolfSSL client. In (D)TLS 1.3 the handshake is encrypted after the ServerHello but a wolfSSL client would accept an unencrypted flight from the server. This does not compromise key negotiation and authentication so it is assigned a low severity rating.

Products
wolfssl
Affected versions
5.5.4-2, 5.5.4-2+deb12u1, 5.5.4-2+deb12u2, 5.5.4-2+deb12u3, 5.5.4-2.1, 5.6.4-1, 5.6.4-2, 5.6.6-1, 5.6.6-1.1, 5.6.6-1.2, 5.6.6-1.3, 5.6.6-1.3~exp1, 5.7.0-0.1, 5.7.0-0.2, 5.7.0-0.3, 5.7.2-0.1, 5.7.2-0.2, 5.7.2-0.3, 5.7.2-0.4, 5.8.2-1, 5.8.2-1.1, 5.8.2-1.2, 5.8.4-1, 5.9.0-0.1, 5.9.0-0.2, 5.9.1-0.1, 5.9.2-1, 5.9.2-1.1, 5.9.2-1.2
Fixed versions
5.6.6-1.2
CVEs
CVE-2023-6937
Confirmed fixed CVEs
Not specified
Updated in this feed
1 Nov 2026, 16:09 UTC · Revision 1

Source evidence

DEBIAN-CVE-2023-6937

core-osv · Original source

Published 15 Feb 2024, 18:15 UTC

wolfSSL prior to 5.6.6 did not check that messages in one (D)TLS record do not span key boundaries. As a result, it was possible to combine (D)TLS messages using different keys into one (D)TLS record. The most extreme edge case is that, in (D)TLS 1.3, it was possible that an unencrypted (D)TLS 1.3 record from the server containing first a ServerHello message and then the rest of the first server flight would be accepted by a wolfSSL client. In (D)TLS 1.3 the handshake is encrypted after the ServerHello but a wolfSSL client would accept an unencrypted flight from the server. This does not compromise key negotiation and authentication so it is assigned a low severity rating.

osv:DEBIAN-CVE-2023-6937

wolfssl

Fixed versions: Not specified

wolfssl

Fixed versions: 5.6.6-1.2

Complete source record
{
  "id": "ebac3215d8c22ed9de518a3294e0c170d9e038b2671f5a3d621dee995ad46071",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2023-6937",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2023-6937",
    "summary": "wolfSSL prior to 5.6.6 did not check that messages in one (D)TLS record do not span key boundaries. As a result, it was possible to combine (D)TLS messages using different keys into one (D)TLS record. The most extreme edge case is that, in (D)TLS 1.3, it was possible that an unencrypted (D)TLS 1.3 record from the server containing first a ServerHello message and then the rest of the first server flight would be accepted by a wolfSSL client. In (D)TLS 1.3 the handshake is encrypted after the ServerHello but a wolfSSL client would accept an unencrypted flight from the server. This does not compromise key negotiation and authentication so it is assigned a low severity rating.",
    "evidence": "osv:DEBIAN-CVE-2023-6937",
    "products": [
      {
        "name": {
          "value": "wolfssl",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "5.5.4-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.5.4-2+deb12u1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.5.4-2+deb12u2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.5.4-2+deb12u3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.5.4-2.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.6.4-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.6.4-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.6.6-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.6.6-1.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.6.6-1.2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.6.6-1.3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.6.6-1.3~exp1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.7.0-0.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.7.0-0.2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.7.0-0.3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.7.2-0.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.7.2-0.2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.7.2-0.3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.7.2-0.4",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.8.2-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.8.2-1.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.8.2-1.2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.8.4-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.9.0-0.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.9.0-0.2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.9.1-0.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.9.2-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.9.2-1.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.9.2-1.2",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "wolfssl",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.6.6-1.2",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "DEBIAN-CVE-2023-6937",
      "aliases": [
        "DEBIAN-CVE-2023-6937"
      ],
      "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": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "wolfssl",
            "purl": "pkg:deb/debian/wolfssl?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "versions": [
            "5.5.4-2",
            "5.5.4-2+deb12u1",
            "5.5.4-2+deb12u2",
            "5.5.4-2+deb12u3",
            "5.5.4-2.1",
            "5.6.4-1",
            "5.6.4-2",
            "5.6.6-1",
            "5.6.6-1.1",
            "5.6.6-1.2",
            "5.6.6-1.3",
            "5.6.6-1.3~exp1",
            "5.7.0-0.1",
            "5.7.0-0.2",
            "5.7.0-0.3",
            "5.7.2-0.1",
            "5.7.2-0.2",
            "5.7.2-0.3",
            "5.7.2-0.4",
            "5.8.2-1",
            "5.8.2-1.1",
            "5.8.2-1.2",
            "5.8.4-1",
            "5.9.0-0.1",
            "5.9.0-0.2",
            "5.9.1-0.1",
            "5.9.2-1",
            "5.9.2-1.1",
            "5.9.2-1.2"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-6937.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "5.6.6-1.2"
                }
              ]
            }
          ],
          "package": {
            "name": "wolfssl",
            "purl": "pkg:deb/debian/wolfssl?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-6937.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-26T18:02:47.386225712Z",
      "provider": "osv",
      "upstream": [
        "CVE-2023-6937"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2023-6937"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2023-6937",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 456846,
  "published_at": "2024-02-15T18:15:44.89+00:00"
}