CVE-2021-22901

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Summary:

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.

Reference Links(if available):

  • https://curl.se/docs/CVE-2021-22901.html
  • https://hackerone.com/reports/1180380
  • https://github.com/curl/curl/commit/7f4a9a9b2a49547eae24d2e19bc5c346e9026479
  • https://www.oracle.com//security-alerts/cpujul2021.html
  • CVSS Score (if available)

    v2: / MEDIUMAV:N/AC:M/Au:N/C:P/I:P/A:P

    v3: / HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

    Links to Exploits(if available)

  • Available for Amazon Prime