CVE-2021-22890

Description


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


Permissions RequiredThird Party Advisory

PatchVendor Advisory

Mailing ListThird Party Advisory

Mailing ListThird Party Advisory

CvssV3 impact


BaseSeverity

LOW

ConfidentialityImpact

NONE

AttackComplexity

HIGH

Scope

UNCHANGED

AttackVector

NETWORK

AvailabilityImpact

NONE

IntegrityImpact

LOW

PrivilegesRequired

NONE

BaseScore

3.7

VectorString

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

Version

3.1

UserInteraction

NONE

CvssV2 impact


AccessComplexity

MEDIUM

ConfidentialityImpact

NONE

AvailabilityImpact

NONE

IntegrityImpact

PARTIAL

BaseScore

4.3

VectorString

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

Version

2.0

AccessVector

NETWORK

Authentication

NONE