CVE-2021-22890

Published: 31 March 2021

curl 7.63.0 to and including 7.75.0 includes vulnerability that allows a malicious HTTPS proxy to MITM a connection due to bad handling of TLS 1.3 session tickets. When using a HTTPS proxy and TLS 1.3, libcurl can confuse session tickets arriving from the HTTPS proxy but work as if they arrived from the remote server and then wrongly "short-cut" the host handshake. When confusing the tickets, a HTTPS proxy can trick libcurl to use the wrong session ticket resume for the host and thereby circumvent the server TLS certificate check and make a MITM attack to be possible to perform unnoticed. Note that such a malicious HTTPS proxy needs to provide a certificate that curl will accept for the MITMed server for an attack to work - unless curl has been told to ignore the server certificate check.

Priority

Medium

CVSS 3 base score: 3.7

Status

Notes

affects curl versions between 7.63.0 and 7.75.0

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-22890
• https://curl.se/docs/CVE-2021-22890.html
• https://ubuntu.com/security/notices/USN-4898-1
• NVD
• Launchpad
• Debian

Bugs