CVE-2021-22925

A flaw was found in the way curl handled telnet protocol option for sending environment variables, which could lead to sending of uninitialized data from a stack-based buffer to the server. This issue leads to potentially revealing sensitive internal information to the server using a clear-text network protocol.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

This issue can be avoided by not setting any telnet options for the curl command line tool (using the -t / --telnet-option command line option) or the libcurl library (using the CURLOPT_TELNETOPTIONS option) when telnet protocol is not meant to be used.

If telnet protocol needs to be used with curl / libcurl, along with the NEW_ENV telnet option, ensure that no environment variable set via the NEW_ENV option has the name or value longer than 127 bytes.