CVE-2026-9545
N/A
N/A
Summary
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uses a proper HTTP/3 server for the initial transfers, and when it makes a second transfer to the same site it has been replaced by the attacker's impostor machine - without a valid certificate.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 Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| curl | curl | 8.20.0 <= 8.20.0 | affected |
| curl | curl | 8.19.0 <= 8.19.0 | affected |
| curl | curl | 8.18.0 <= 8.18.0 | affected |
| curl | curl | 8.17.0 <= 8.17.0 | affected |
| curl | curl | 8.16.0 <= 8.16.0 | affected |
| curl | curl | 8.15.0 <= 8.15.0 | affected |
| curl | curl | 8.14.1 <= 8.14.1 | affected |
| curl | curl | 8.14.0 <= 8.14.0 | affected |
| curl | curl | 8.13.0 <= 8.13.0 | affected |
| curl | curl | 8.12.1 <= 8.12.1 | affected |
| curl | curl | 8.12.0 <= 8.12.0 | affected |
| curl | curl | 8.11.1 <= 8.11.1 | affected |
| curl | curl | 8.11.0 <= 8.11.0 | affected |
Weaknesses
- CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
References
- https://curl.se/docs/CVE-2026-9545.json
- https://curl.se/docs/CVE-2026-9545.html
- https://hackerone.com/reports/3752888
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