{"id":"UBUNTU-CVE-2021-22901","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content into the correct place in memory.","modified":"2025-07-16T08:15:31.759450Z","published":"2021-05-26T06:00:00Z","withdrawn":"2025-07-18T16:46:39Z","upstream":["CVE-2021-22901"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-22901"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2021-22901"}],"affected":[{"package":{"name":"curl","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/curl@7.58.0-2ubuntu3.13?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"7.58.0-2ubuntu3.13"}]}],"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":{"binaries":[{"binary_version":"7.58.0-2ubuntu3.13","binary_name":"curl"},{"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_version":"7.58.0-2ubuntu3.13","binary_name":"libcurl4-gnutls-dev"},{"binary_name":"libcurl4-nss-dev","binary_version":"7.58.0-2ubuntu3.13"},{"binary_name":"libcurl4-openssl-dev","binary_version":"7.58.0-2ubuntu3.13"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-22901.json"}},{"package":{"name":"curl","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/curl@7.68.0-1ubuntu2.5?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"7.68.0-1ubuntu2.5"}]}],"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"],"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_version":"7.68.0-1ubuntu2.5","binary_name":"libcurl4"},{"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"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-22901.json"}}],"schema_version":"1.7.3","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}