Descriptioncurl 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
curl (PTS)stretch7.52.1-5+deb9u10fixed
stretch (security)7.52.1-5+deb9u16fixed
buster, buster (security)7.64.0-4+deb10u2fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
curlsource(unstable)(not affected)


- curl <not-affected> (Vulnerable code introduced later)
Introduced by: (7.75.0)
Fixed by: (7.77.0)

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