CVE-2021-22901
Use After Free: Is CVE-2021-22901 real, exploitable, or a false positive? Here's the community verdict.
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signals
public sources
High severity and high exploitation probability. Prioritise remediation.
baseline read
auto · not a community verdict
Likely real & worth prioritising
High base severity and a high real-world exploitation probability both point to a genuine, actively targeted issue.
Based on CVSS · FIRST EPSS
Confirm or dispute →CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
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.
References
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