ubuntu-cve-2021-22901
Vulnerability from osv_ubuntu
Published
2021-05-26 06:00
Modified
2025-07-16 04:57
Summary
Details

curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability resulting in already freed memory being used when a TLS 1.3 session ticket arrives over a connection. A malicious server can use this in rare unfortunate circumstances to potentially reach remote code execution in the client. When libcurl at run-time sets up support for TLS 1.3 session tickets on a connection using OpenSSL, it stores pointers to the transfer in-memory object for later retrieval when a session ticket arrives. If the connection is used by multiple transfers (like with a reused HTTP/1.1 connection or multiplexed HTTP/2 connection) that first transfer object might be freed before the new session is established on that connection and then the function will access a memory buffer that might be freed. When using that memory, libcurl might even call a function pointer in the object, making it possible for a remote code execution if the server could somehow manage to get crafted memory content into the correct place in memory.

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

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "curl",
            "binary_version": "7.58.0-2ubuntu3.13"
          },
          {
            "binary_name": "curl-dbgsym",
            "binary_version": "7.58.0-2ubuntu3.13"
          },
          {
            "binary_name": "libcurl3-gnutls",
            "binary_version": "7.58.0-2ubuntu3.13"
          },
          {
            "binary_name": "libcurl3-gnutls-dbgsym",
            "binary_version": "7.58.0-2ubuntu3.13"
          },
          {
            "binary_name": "libcurl3-nss",
            "binary_version": "7.58.0-2ubuntu3.13"
          },
          {
            "binary_name": "libcurl3-nss-dbgsym",
            "binary_version": "7.58.0-2ubuntu3.13"
          },
          {
            "binary_name": "libcurl4",
            "binary_version": "7.58.0-2ubuntu3.13"
          },
          {
            "binary_name": "libcurl4-dbgsym",
            "binary_version": "7.58.0-2ubuntu3.13"
          },
          {
            "binary_name": "libcurl4-doc",
            "binary_version": "7.58.0-2ubuntu3.13"
          },
          {
            "binary_name": "libcurl4-gnutls-dev",
            "binary_version": "7.58.0-2ubuntu3.13"
          },
          {
            "binary_name": "libcurl4-nss-dev",
            "binary_version": "7.58.0-2ubuntu3.13"
          },
          {
            "binary_name": "libcurl4-openssl-dev",
            "binary_version": "7.58.0-2ubuntu3.13"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "curl",
        "purl": "pkg:deb/ubuntu/curl@7.58.0-2ubuntu3.13?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.58.0-2ubuntu3.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "7.55.1-1ubuntu2",
        "7.55.1-1ubuntu2.1",
        "7.57.0-1ubuntu1",
        "7.58.0-2ubuntu1",
        "7.58.0-2ubuntu2",
        "7.58.0-2ubuntu3",
        "7.58.0-2ubuntu3.1",
        "7.58.0-2ubuntu3.2",
        "7.58.0-2ubuntu3.3",
        "7.58.0-2ubuntu3.5",
        "7.58.0-2ubuntu3.6",
        "7.58.0-2ubuntu3.7",
        "7.58.0-2ubuntu3.8",
        "7.58.0-2ubuntu3.9",
        "7.58.0-2ubuntu3.10",
        "7.58.0-2ubuntu3.12"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "curl",
            "binary_version": "7.68.0-1ubuntu2.5"
          },
          {
            "binary_name": "curl-dbgsym",
            "binary_version": "7.68.0-1ubuntu2.5"
          },
          {
            "binary_name": "libcurl3-gnutls",
            "binary_version": "7.68.0-1ubuntu2.5"
          },
          {
            "binary_name": "libcurl3-gnutls-dbgsym",
            "binary_version": "7.68.0-1ubuntu2.5"
          },
          {
            "binary_name": "libcurl3-nss",
            "binary_version": "7.68.0-1ubuntu2.5"
          },
          {
            "binary_name": "libcurl3-nss-dbgsym",
            "binary_version": "7.68.0-1ubuntu2.5"
          },
          {
            "binary_name": "libcurl4",
            "binary_version": "7.68.0-1ubuntu2.5"
          },
          {
            "binary_name": "libcurl4-dbgsym",
            "binary_version": "7.68.0-1ubuntu2.5"
          },
          {
            "binary_name": "libcurl4-doc",
            "binary_version": "7.68.0-1ubuntu2.5"
          },
          {
            "binary_name": "libcurl4-gnutls-dev",
            "binary_version": "7.68.0-1ubuntu2.5"
          },
          {
            "binary_name": "libcurl4-nss-dev",
            "binary_version": "7.68.0-1ubuntu2.5"
          },
          {
            "binary_name": "libcurl4-openssl-dev",
            "binary_version": "7.68.0-1ubuntu2.5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "curl",
        "purl": "pkg:deb/ubuntu/curl@7.68.0-1ubuntu2.5?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.68.0-1ubuntu2.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "7.65.3-1ubuntu3",
        "7.65.3-1ubuntu4",
        "7.66.0-1ubuntu1",
        "7.67.0-2ubuntu1",
        "7.68.0-1ubuntu1",
        "7.68.0-1ubuntu2",
        "7.68.0-1ubuntu2.1",
        "7.68.0-1ubuntu2.2",
        "7.68.0-1ubuntu2.4"
      ]
    }
  ],
  "aliases": [],
  "details": "curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability resulting in already freed memory being used when a TLS 1.3 session ticket arrives over a connection. A malicious server can use this in rare unfortunate circumstances to potentially reach remote code execution in the client. When libcurl at run-time sets up support for TLS 1.3 session tickets on a connection using OpenSSL, it stores pointers to the transfer in-memory object for later retrieval when a session ticket arrives. If the connection is used by multiple transfers (like with a reused HTTP/1.1 connection or multiplexed HTTP/2 connection) that first transfer object might be freed before the new session is established on that connection and then the function will access a memory buffer that might be freed. When using that memory, libcurl might even call a function pointer in the object, making it possible for a remote code execution if the server could somehow manage to get crafted memory content into the correct place in memory.",
  "id": "UBUNTU-CVE-2021-22901",
  "modified": "2025-07-16T04:57:01Z",
  "published": "2021-05-26T06:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2021-22901"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2021-22901"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2021-22901"
  ],
  "withdrawn": "2025-07-18T16:46:39Z"
}



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