CVE-2026-9545 Affecting libcurl-openssl4 package, versions <8.21.0-r0


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.41% (33rd percentile)

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  • Snyk IDSNYK-MINIMOSLATEST-LIBCURLOPENSSL4-17897162
  • published9 Jul 2026
  • disclosed3 Jul 2026

Introduced: 3 Jul 2026

NewCVE-2026-9545  (opens in a new tab)

How to fix?

Upgrade Minimos:latest libcurl-openssl4 to version 8.21.0-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libcurl-openssl4 package and not the libcurl-openssl4 package as distributed by Minimos. See How to fix? for Minimos:latest relevant fixed versions and status.

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uses a proper HTTP/3 server for the initial transfers, and when it makes a second transfer to the same site it has been replaced by the attacker's impostor machine - without a valid certificate.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

CVSS Base Scores

version 3.1