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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-22890
• https://hackerone.com/reports/1129529
• https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
• https://curl.se/docs/CVE-2021-22890.html
• https://security.gentoo.org/glsa/202105-36
• https://www.oracle.com//security-alerts/cpujul2021.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2ZC5BMIOKLBQJSFCHEDN2G2C2SH274BP
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ITVWPVGLFISU5BJC2BXBRYSDXTXE2YGC
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KQUIOYX2KUU6FIUZVB5WWZ6JHSSYSQWJ
• https://lists.fedoraproject.org/archives/list/[email protected]/message/2ZC5BMIOKLBQJSFCHEDN2G2C2SH274BP
• https://lists.fedoraproject.org/archives/list/[email protected]/message/ITVWPVGLFISU5BJC2BXBRYSDXTXE2YGC
• https://lists.fedoraproject.org/archives/list/[email protected]/message/KQUIOYX2KUU6FIUZVB5WWZ6JHSSYSQWJ
• https://security.netapp.com/advisory/ntap-20210521-0007