CVE-2021-22901
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.
Published Jun 11, 2021 · updated Oct 14, 2026 · haxx curl
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.
Code
The project this record applies to. Exploit listings stay in References.
Timeline
Detection, updates, and resolution for this record.
Jun 11, 2021 · NIST NVD
Detected
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
Oct 14, 2026 · NIST NVD
Updated
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
Affected
- cpe haxx/curlversion unspecified
- cpe netapp/active iq unified managerversion unspecified
- cpe netapp/h300e firmwareversion unspecified
- cpe netapp/h300s firmwareversion unspecified
- cpe netapp/hci compute node firmwareversion unspecified
- cpe oracle/communications cloud native core binding support function1.11.0
- cpe oracle/communications cloud native core network function cloud native environment1.10.0
- cpe oracle/communications cloud native core network repository function1.15.0
- cpe oracle/communications cloud native core network repository function1.15.1
- cpe oracle/communications cloud native core network slice selection function1.8.0
- cpe oracle/communications cloud native core service communication proxy1.15.0
- cpe oracle/essbaseversion unspecified
Sources
- CVE.orgVulnerability recordCVE-2021-22901
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2021-22901
30-day exploitation probability 63.5%
first.org - NIST NVDVulnerability recordCVE-2021-22901
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 executio
nvd.nist.gov