Apache HttpClient: SCRAM-SHA-256 mutual authentication bypass may cause the client to accept authentication without proper mutual authentication verification

{
  "id": "f1fe374f0afd7a71ee3379b6ab955505754ed3eaa9c5e0b0f5fe39d6f7f8f0a1",
  "url": "https://osv.dev/vulnerability/CVE-2026-40542",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Apache HttpClient: SCRAM-SHA-256 mutual authentication bypass may cause the client to accept authentication without proper mutual authentication verification",
    "summary": "Missing critical step in authentication in Apache HttpClient 5.6 allows an attacker to cause the client to accept SCRAM-SHA-256 authentication without proper mutual authentication verification. Users are recommended to upgrade to version 5.6.1, which fixes this issue.",
    "evidence": "osv:CVE-2026-40542",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-40542",
      "aliases": [
        "CVE-2026-40542",
        "GHSA-v468-qcjx-r72w"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/apache/httpcomponents-client",
              "type": "GIT",
              "events": [
                {
                  "introduced": "decd193d2b615fa18146a9f8392f201d736faf4b"
                },
                {
                  "last_affected": "decd193d2b615fa18146a9f8392f201d736faf4b"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:apache:httpclient:5.6:-:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "5.6-NA"
                      },
                      {
                        "last_affected": "5.6-NA"
                      }
                    ],
                    "source": "CPE_STRING"
                  }
                ]
              }
            }
          ],
          "versions": [
            "5.6-NA",
            "rel/v5.6",
            "5.6-RC1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-40542.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:52.583803166Z",
      "provider": "osv",
      "references": [
        "https://repo.maven.apache.org/maven2",
        "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40542.json",
        "https://access.redhat.com/errata/RHSA-2026:60239",
        "https://access.redhat.com/errata/RHSA-2026:60246",
        "https://access.redhat.com/errata/RHSA-2026:60247",
        "https://access.redhat.com/errata/RHSA-2026:60248",
        "https://access.redhat.com/errata/RHSA-2026:60249",
        "https://access.redhat.com/errata/RHSA-2026:60250",
        "https://access.redhat.com/errata/RHSA-2026:60251",
        "https://access.redhat.com/errata/RHSA-2026:60252",
        "https://access.redhat.com/errata/RHSA-2026:60254",
        "https://access.redhat.com/errata/RHSA-2026:60256",
        "https://access.redhat.com/errata/RHSA-2026:60259",
        "https://access.redhat.com/security/cve/CVE-2026-40542",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40542.json",
        "https://lists.apache.org/thread/tfmgv86xr0z1y096vs3z0y315t1v3o97",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-40542",
        "https://bugzilla.redhat.com/show_bug.cgi?id=2460518"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-304"
        ],
        "cna_assigner": "apache",
        "unresolved_ranges": [
          {
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "5.6"
                  },
                  {
                    "fixed": "5.6.1"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StandardRange"
              }
            ]
          }
        ],
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40542.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-40542",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 521441,
  "published_at": "2026-04-22T07:07:21.344+00:00"
}