CVE-2021-22890

Publication date 31 March 2021

Last updated 24 July 2024

Ubuntu priority

Cvss 3 Severity Score

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.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
curl	20.10 groovy	Fixed 7.68.0-1ubuntu4.3
	20.04 LTS focal	Fixed 7.68.0-1ubuntu2.5
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

Notes

alexmurray

affects curl versions between 7.63.0 and 7.75.0

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
curl	Vendor: https://curl.se/EQo2A9nBnMI68.patch

Severity score breakdown

Parameter	Value
Base score	3.7 · Low
Attack vector	Network
Attack complexity	High
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	Low
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

References

Related Ubuntu Security Notices (USN)

USN-4898-1
curl vulnerabilities
31 March 2021