Description


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uses a proper HTTP/3 server for the initial transfers, and when it makes a second transfer to the same site it has been replaced by the attacker's impostor machine - without a valid certificate.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 `CURLSSLOPT_EARLYDATA` bit is set in `CURLOPT_SSL_OPTIONS`), libcurl might send off the second request's bytes on that new connection *before* enforcing the certificate verification failure. Potentially leaking sensitive information.

Related CPE's


Vulnerable

References




https://hackerone.com/reports/3752888

ExploitIssue TrackingThird Party Advisory

https://hackerone.com/reports/3752888

ExploitIssue TrackingThird Party Advisory

Weaknesses


2499f714-1537-4658-8207-48ae4bb9eae9

Secondary

CWE-200


NVD-CWE-noinfo

CVSS impact metrics


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

7.5 · High

Information


Source identifier

2499f714-1537-4658-8207-48ae4bb9eae9

Vulnerability status

Modified

Published

2026-07-03T07:16:25.807Z

3 months ago

Last modified

2026-09-15T07:16:34.947Z

3 weeks ago