CVE-2021-22897: curl 7.61.0 through 7.76.1 suffers from exposure of data element to wrong session due to a mistake in the code for CURLOPT_SSL_CIPHER_LIST when libcurl is built to use the Schannel TLS library. The selected cipher set was stored in a single "static" variable in the library which has the surprising 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.

Overview

Severity: Medium (CVSS 5.3)
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Exploit Status: Not Exploited
Patch Tuesday: 2021-Jun
Released: 2021-06-23
Last Updated: 2021-12-16
EPSS Score: 0.79% (percentile: 73.9%)

FAQ

Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability? One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.

Overview

FAQ

Affected Products (2)

Other

Revision History