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[email protected]/message/ITVWPVGLFISU5BJC2BXBRYSDXTXE2YGC/[email protected]/message/KQUIOYX2KUU6FIUZVB5WWZ6JHSSYSQWJ/[email protected]/message/2ZC5BMIOKLBQJSFCHEDN2G2C2SH274BP/


Source: MITRE

Published: 2021-04-01

Updated: 2022-04-06

Type: CWE-290

Risk Information


Base Score: 4.3

Vector: AV:N/AC:M/Au:N/C:N/I:P/A:N

Impact Score: 2.9

Exploitability Score: 8.6

Severity: MEDIUM


Base Score: 3.7

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Impact Score: 1.4

Exploitability Score: 2.2

Severity: LOW