CVE-2026-9545EPSS p19.0%
CVE-2026-9545CVE-2026-9545
haxx / curl
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transfers, and when it makes a second transfer to the same site it has been
replaced by the attacker's impostor machine - without a valid certificate.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.
Scoring
| CVSS | 7.5 () |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
| EPSS | 0.27% probability of exploitation · percentile 19.0% · 2026-08-17T12:03:47Z |
| Last modified | 2026-07-07 |