FKIE_CVE-2026-4873

Vulnerability from fkie_nvd - Published: 2026-05-13 13:01 - Updated: 2026-05-14 13:45
Severity
5.9 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Summary
A vulnerability exists where a connection requiring TLS incorrectly reuses an existing unencrypted connection from the same connection pool. If an initial transfer is made in clear-text (via IMAP, SMTP, or POP3), a subsequent request to that same host bypasses the TLS requirement and instead transmit data unencrypted.
References
2499f714-1537-4658-8207-48ae4bb9eae9https://curl.se/docs/CVE-2026-4873.htmlPatch, Vendor Advisory
2499f714-1537-4658-8207-48ae4bb9eae9https://curl.se/docs/CVE-2026-4873.jsonVendor Advisory
2499f714-1537-4658-8207-48ae4bb9eae9https://hackerone.com/reports/3621851Exploit, Issue Tracking, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108http://www.openwall.com/lists/oss-security/2026/04/29/7Mailing List, Patch, Third Party Advisory
Impacted products
Vendor Product Version
haxx curl *
To clipboard 

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    {
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            {
              "criteria": "cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "50906082-180F-4E8B-A3E5-AC2C14B54B89",
              "versionEndExcluding": "8.20.0",
              "versionStartIncluding": "7.20.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A vulnerability exists where a connection requiring TLS incorrectly reuses an\nexisting unencrypted connection from the same connection pool. If an initial\ntransfer is made in clear-text (via IMAP, SMTP, or POP3), a subsequent request\nto that same host bypasses the TLS requirement and instead transmit data\nunencrypted."
    }
  ],
  "id": "CVE-2026-4873",
  "lastModified": "2026-05-14T13:45:11.407",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.9,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 3.6,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-05-13T13:01:55.893",
  "references": [
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Patch",
        "Vendor Advisory"
      ],
      "url": "https://curl.se/docs/CVE-2026-4873.html"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
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      "url": "https://curl.se/docs/CVE-2026-4873.json"
    },
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      "tags": [
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        "Issue Tracking",
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      "url": "https://hackerone.com/reports/3621851"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
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        "Patch",
        "Third Party Advisory"
      ],
      "url": "http://www.openwall.com/lists/oss-security/2026/04/29/7"
    }
  ],
  "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-295"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-319"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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