free5GC AUSF uses non-constant-time authentication comparisons and logs XRES* in 5G-AKA

{
  "id": "d0a9da667645660c6f9af05ac014b2ad247c7a5bc7ad7aeca83dd60368242a93",
  "url": "https://osv.dev/vulnerability/CVE-2026-55785",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "free5GC AUSF uses non-constant-time authentication comparisons and logs XRES* in 5G-AKA",
    "summary": "free5GC is an open-source implementation of the 5G core network. Prior to 1.4.5, the AUSF component performs cryptographic authentication comparisons in internal/sbi/processor/ue_authentication.go with ordinary equality helpers. Auth5gAkaComfirmRequestProcedure compares RES* and XRES* with strings.EqualFold and logs the expected XRES* value at INFO level before comparison. EapAuthComfirmRequestProcedure compares AT_MAC and XMAC with bytes.Equal and evaluates XRES == RES with ordinary string equality. These comparisons can return at mismatch-dependent times, although testing did not demonstrate a practical remote timing oracle because of HTTP/SBI timing noise. The INFO log exposes authentication material to operators, log collectors, sidecars, or processes able to read AUSF logs. This issue is fixed in version 1.4.5.",
    "evidence": "osv:CVE-2026-55785",
    "products": [],
    "severity": "low",
    "structured": {
      "id": "CVE-2026-55785",
      "aliases": [
        "CVE-2026-55785",
        "GHSA-fp46-6vfw-gc9c",
        "GO-2026-6328"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/free5gc/ausf",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "b74ee7dafec5975e3440ae95125994565cfb0496"
                },
                {
                  "fixed": "7a5a4aa1ec6cd0e1febebf333911c3104968edf0"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.4.5"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "7a5a4aa1ec6cd0e1febebf333911c3104968edf0"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "b74ee7dafec5975e3440ae95125994565cfb0496"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v1.4.5"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.4.4",
            "v1.4.3",
            "v1.4.2",
            "v1.4.1",
            "v1.4.0",
            "v1.3.2",
            "v1.3.1",
            "v1.3.0",
            "v1.2.4",
            "v1.2.3",
            "v1.2.2",
            "v1.2.1",
            "v1.2.0",
            "v1.1.1",
            "v1.1.0",
            "v1.0.2",
            "v1.0.1",
            "v1.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-55785.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:29.158896688Z",
      "provider": "osv",
      "references": [
        "https://github.com/free5gc/ausf/releases/tag/v1.4.5",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55785.json",
        "https://github.com/free5gc/free5gc/security/advisories/GHSA-fp46-6vfw-gc9c",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-55785",
        "https://github.com/free5gc/ausf/commit/7a5a4aa1ec6cd0e1febebf333911c3104968edf0",
        "https://github.com/free5gc/ausf/pull/63"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-208",
          "CWE-385",
          "CWE-532"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55785.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-55785",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 495755,
  "published_at": "2026-08-28T22:25:06.814+00:00"
}