CVE-2021-22897

A flaw was found in curl where libcurl lets applications specify which specific TLS ciphers to use in transfers, using the option called CURLOPT_SSL_CIPHER_LIST. The cipher selection is used for the TLS negotiation when a transfer is done involving any of the TLS based transfer protocols libcurl supports, such as HTTPS, FTPS, IMAPS, POP3S, SMTPS, etc. Due to a mistake in the code, the selected cipher set was stored in a single "static" variable in the library, which contains a side-effect that if an application sets up multiple concurrent transfers, the last one that sets the ciphers will accidentally control the set used by all transfers. In a worst-case scenario, this weakens transport security significantly. The highest threat from this vulnerability is to confidentiality.

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.