CRITICAL · 9.1

CVE-2026-34873

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.

Vulnerability Description

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.

CVSS Score

9.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE

Affected Products

VendorProductVersions
ArmMbed Tls>= 3.5.0, < 3.6.6

Related Weaknesses (CWE)

References

FAQ

What is CVE-2026-34873?

CVE-2026-34873 is a vulnerability with a CVSS score of 9.1 (CRITICAL). 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.

How severe is CVE-2026-34873?

CVE-2026-34873 has been rated CRITICAL with a CVSS base score of 9.1/10. This is considered a critical vulnerability requiring immediate attention.

Is there a patch for CVE-2026-34873?

Check the references section above for vendor advisories and patch information. Affected products include: Arm Mbed Tls.