Bug 2454108 (CVE-2026-34873)

Summary: CVE-2026-34873 mbedtls: Mbed TLS: Client impersonation during TLS 1.3 session resumption
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: urgent Docs Contact:
Priority: urgent    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Mbed TLS. This vulnerability allows a remote attacker to impersonate a client during the resumption of a TLS 1.3 session. This could lead to unauthorized access or other security breaches by allowing the attacker to act as a legitimate client.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2454191, 2454192, 2454193, 2454194, 2454196    
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Description OSIDB Bzimport 2026-04-01 21:02:57 UTC
An issue was discovered in Mbed TLS 3.5.0 through 4.0.0. Client impersonation can occur while resuming a TLS 1.3 session.