UBUNTU-CVE-2026-9545 (CVE-2026-9545)

Vulnerability from osv_ubuntu – Published: 2026-06-24 14:00 – Updated: 2026-07-09 15:15 – Source website
VLAI
Details

In this scenario, libcurl first uses a proper HTTP/3 server for the initial transfers, and when it makes a second transfer to the same site it has been replaced by the attacker's impostor machine - without a valid certificate. When libcurl returns to the hostname the second time with a cached SSL session (CURLOPT_SSL_SESSIONID_CACHE is not disabled) and early data enabled (the CURLSSLOPT_EARLYDATA bit is set in CURLOPT_SSL_OPTIONS), libcurl might send off the second request's bytes on that new connection before enforcing the certificate verification failure. Potentially leaking sensitive information.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
N/A (UNKNOWN)
low
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "curl",
            "binary_version": "8.14.1-2ubuntu1.4"
          },
          {
            "binary_name": "libcurl3t64-gnutls",
            "binary_version": "8.14.1-2ubuntu1.4"
          },
          {
            "binary_name": "libcurl4t64",
            "binary_version": "8.14.1-2ubuntu1.4"
          }
        ],
        "priority_reason": "Upstream defined this as low severity"
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "curl",
        "purl": "pkg:deb/ubuntu/curl@8.14.1-2ubuntu1.4?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.14.1-2ubuntu1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.12.1-3ubuntu1",
        "8.13.0-5ubuntu1",
        "8.14.1-1ubuntu2",
        "8.14.1-1ubuntu3",
        "8.14.1-2ubuntu1",
        "8.14.1-2ubuntu1.1",
        "8.14.1-2ubuntu1.2",
        "8.14.1-2ubuntu1.3"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "curl",
            "binary_version": "8.18.0-1ubuntu2.2"
          },
          {
            "binary_name": "libcurl3t64-gnutls",
            "binary_version": "8.18.0-1ubuntu2.2"
          },
          {
            "binary_name": "libcurl4t64",
            "binary_version": "8.18.0-1ubuntu2.2"
          }
        ],
        "priority_reason": "Upstream defined this as low severity"
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "curl",
        "purl": "pkg:deb/ubuntu/curl@8.18.0-1ubuntu2.2?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.18.0-1ubuntu2.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.14.1-2ubuntu1",
        "8.17.0-1ubuntu1",
        "8.18.0-1ubuntu1",
        "8.18.0-1ubuntu2",
        "8.18.0-1ubuntu2.1"
      ]
    }
  ],
  "aliases": [],
  "details": "In this scenario, libcurl first uses a proper HTTP/3 server for the initial transfers, and when it makes a second transfer to the same site it has been replaced by the attacker\u0027s impostor machine - without a valid certificate. When libcurl returns to the hostname the second time with a cached SSL session (`CURLOPT_SSL_SESSIONID_CACHE` is not disabled) and early data enabled (the `CURLSSLOPT_EARLYDATA` bit is set in `CURLOPT_SSL_OPTIONS`), libcurl might send off the second request\u0027s bytes on that new connection *before* enforcing the certificate verification failure. Potentially leaking sensitive information.",
  "id": "UBUNTU-CVE-2026-9545",
  "modified": "2026-07-09T15:15:43Z",
  "published": "2026-06-24T14:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-9545"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-9545"
    },
    {
      "type": "REPORT",
      "url": "https://curl.se/L7HzKXisfJ/CVE-2026-9545.md"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8487-1"
    }
  ],
  "related": [
    "USN-8487-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "low",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-9545"
  ]
}



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