FKIE_CVE-2026-5545

Vulnerability from fkie_nvd - Published: 2026-05-13 13:01 - Updated: 2026-05-13 19:31
Severity
6.5 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
6.5 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
Summary
libcurl might in some circumstances reuse the wrong connection when asked to do an authenticated HTTP(S) request after a Negotiate-authenticated one, when both use the same host. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criteria must be met. Due to a logical error in the code, a request that was issued by an application could wrongfully reuse an existing connection to the same server that was authenticated using different credentials. An application that first uses Negotiate authentication to a server with `user1:password1` and then does another operation to the same server asking for any authentication method but for `user2:password2` (while the previous connection is still alive) - the second request gets confused and wrongly reuses the same connection and sends the new request over that connection thinking it uses a mix of user1's and user2's credentials when it is in fact still using the connection authenticated for user1...
References
2499f714-1537-4658-8207-48ae4bb9eae9https://curl.se/docs/CVE-2026-5545.htmlPatch, Vendor Advisory
2499f714-1537-4658-8207-48ae4bb9eae9https://curl.se/docs/CVE-2026-5545.jsonVendor Advisory
2499f714-1537-4658-8207-48ae4bb9eae9https://hackerone.com/reports/3642555Exploit, Issue Tracking, Third Party Advisory
134c704f-9b21-4f2e-91b3-4a467353bcc0https://hackerone.com/reports/3642555Exploit, Issue Tracking, Third Party Advisory
Impacted products
Vendor Product Version
haxx curl *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "6863ED61-1229-415E-BB05-C827893B6CED",
              "versionEndExcluding": "8.20.0",
              "versionStartIncluding": "7.10.6",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "libcurl might in some circumstances reuse the wrong connection when asked to\ndo an authenticated HTTP(S) request after a Negotiate-authenticated one, when\nboth use the same host.\n\nlibcurl features a pool of recent connections so that subsequent requests can\nreuse an existing connection to avoid overhead.\n\nWhen reusing a connection a range of criteria must be met. Due to a logical\nerror in the code, a request that was issued by an application could\nwrongfully reuse an existing connection to the same server that was\nauthenticated using different credentials.\n\nAn application that first uses Negotiate authentication to a server with\n`user1:password1` and then does another operation to the same server asking\nfor any authentication method but for `user2:password2` (while the previous\nconnection is still alive) - the second request gets confused and wrongly\nreuses the same connection and sends the new request over that connection\nthinking it uses a mix of user1\u0027s and user2\u0027s credentials when it is in fact\nstill using the connection authenticated for user1..."
    }
  ],
  "id": "CVE-2026-5545",
  "lastModified": "2026-05-13T19:31:07.633",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 4.2,
        "source": "nvd@nist.gov",
        "type": "Primary"
      },
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 4.2,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-05-13T13:01:56.190",
  "references": [
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Patch",
        "Vendor Advisory"
      ],
      "url": "https://curl.se/docs/CVE-2026-5545.html"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://curl.se/docs/CVE-2026-5545.json"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "url": "https://hackerone.com/reports/3642555"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "url": "https://hackerone.com/reports/3642555"
    }
  ],
  "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-613"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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