Bug 2553428

Summary: CVE-2026-9545 rust: libcurl: Information disclosure via cached SSL session and early data [fedora-all]
Product: [Fedora] Fedora Reporter: Avinash Hanwate <ahanwate>
Component: rustAssignee: Rust SIG <rust-sig>
Status: CLOSED NOTABUG QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: medium    
Version: rawhideCC: amulhern, igor.raits, jchecahi, jistone, paumurph, rust-sig
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["9886f3a2-7f7e-40f5-b367-3b9043f51dc2"]}
Fixed In Version: Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2026-10-15 18:59:36 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2496756    

Description Avinash Hanwate 2026-10-15 12:52:20 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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transfers, and when it makes a second transfer to the same site it has been
replaced by the attacker's impostor machine - without a valid certificate.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.
Comment 1 Josh Stone 2026-10-15 18:59:36 UTC 
The bundled `curl` sources (via the Rust `curl-sys` crate) are wholly removed during the `%prep` phase to be sure we don't use them. Instead, we use the system `curl` library, so any CVE fixes only need to be made in that component on its own.