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Servers and applications

CVE-2026-9545

In this scenario, libcurl first uses a proper HTTP/3 server for the initial transfers, and when it makes a second transfer to the same site it has been replaced by the attacker's impostor machine - without a valid certificate. When libcurl returns to the hostname the second time with a cached SSL session (`CURLOPT_SSL_SESSIONID_CACHE` is not disabled) and early data enabled (the…

Severity
High 7.5
Published
3 Jul 2026
Last changed
15 Sept 2026
Added to UpHeron
21 Oct 2026
Fixed in
8.21.0
Sources
NVD

Affected software

SoftwareAffected versions
curlServers and applications · cpe:a:haxx:curl
  • From 8.11.0 before 8.21.0

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2026-9545
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2026-9545