CVE-2021-22890

high
Published — · Modified —
CVSS v3
CVSS v2
VIR risk
8.0

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.

Predictions

Exploit likelihood
20%
Patch ETA

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2021-22890.html

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2021-22890

OS impact

OSVersionStatusFixed in
arch archfixed7.76.0-1
debian debianbookwormfixed7.74.0-1.2
debian debianbullseyefixed7.74.0-1.2
debian debianforkyfixed7.74.0-1.2
debian debiansidfixed7.74.0-1.2
debian debiantrixiefixed7.74.0-1.2
suse slesaffected

References

Verify integrity in audit chain (admin only). AS-IS.