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CVE-2026-9545

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uses a proper HTTP/3 server for the initial transfers, and when it makes a second transfer to the same site it has been replaced by the attacker's impostor machine - without a valid certificate.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.

Metadata

CVE ID
CVE-2026-9545
State
PUBLISHED
Assigner
curl
Reserved
2026-05-26 06:45 UTC
Published
2026-07-03 06:17 UTC
Last updated
2026-07-03 06:17 UTC
Vendor / Product
curl / curl
Sources
cve.org  ·  NVD

Severity & Metrics

No CVSS data available.

Affected products (1)
VendorProductPlatformVersions
curl curl 8.20.0 ≤ 8.20.0, 8.19.0 ≤ 8.19.0, 8.18.0 ≤ 8.18.0, 8.17.0 ≤ 8.17.0 …
Weakness (CWE)
CWESourceDescription
cna CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
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