CVEvulnerability
CVE-2026-9545
7.5 HIGH
Official page ↗
- Status
- Modified
- Published
- 2026-07-03
- Last modified
- 2026-09-15
- Assigner
- 2499f714-1537-4658-8207-48ae4bb9eae9
- CVSS 3.1 (134c704f-9b21-4f2e-91b3-4a467353bcc0)
- 7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Weaknesses
- CWE-200
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transfers, and when it makes a second transfer to the same site it has been
replaced by the attacker's impostor machine - without a valid certificate.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.
Affected configurations
• haxx curl (>= 8.11.0 < 8.21.0)
Related
Weakness · CWE (1)
- CWE-200 Exposure of Sensitive Information to an Unauthorized Actor weakness
References
- https://curl.se/docs/CVE-2026-9545.html Patch, Vendor Advisory
- https://curl.se/docs/CVE-2026-9545.json Vendor Advisory
- https://hackerone.com/reports/3752888 Exploit, Issue Tracking, Third Party Advisory
- https://hackerone.com/reports/3752888 Exploit, Issue Tracking, Third Party Advisory