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Findings

CVE-2021-22890

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.

Published Apr 1, 2021 · updated Oct 14, 2026 · haxx libcurl

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.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 1, 2021 · NIST NVD

    Detected

    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 HT

  2. Oct 14, 2026 · NIST NVD

    Updated

    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 HT

Affected

  • cpe broadcom/fabric operating systemversion unspecified
  • cpe debian/debian linux9.0
  • cpe fedoraproject/fedora32
  • cpe fedoraproject/fedora33
  • cpe fedoraproject/fedora34
  • cpe haxx/libcurlversion unspecified
  • cpe netapp/hci management nodeversion unspecified
  • cpe netapp/hci storage nodeversion unspecified
  • cpe netapp/solidfireversion unspecified
  • cpe oracle/communications billing and revenue management12.0.0.3.0
  • cpe siemens/sinec infrastructure network servicesversion unspecified
  • cpe splunk/universal forwarderversion unspecified

Sources

  • CVE.orgVulnerability recordCVE-2021-22890

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2021-22890

    30-day exploitation probability 3.1%

    first.org
  • NIST NVDVulnerability recordCVE-2021-22890

    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

    nvd.nist.gov

References