CVE-2026-34877

Name: CVE-2026-34877
Creator: NVD / NIST
Published: 2026-04-02T17:16:26.927+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 0.43%

Last modified Jun 17, 2026

CVE-2026-34877 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. An issue was discovered in Mbed TLS versions from 2.19.0 up to 3.6.5, Mbed TLS 4.0.0. Insufficient protection of serialized SSL context or session structures allows an attacker who can modify the serialized structures to induce memory corruption, leading to arbitrary code execution. EPSS estimates a 0.43% chance of exploitation in the next 30 days.

Description

An issue was discovered in Mbed TLS versions from 2.19.0 up to 3.6.5, Mbed TLS 4.0.0. Insufficient protection of serialized SSL context or session structures allows an attacker who can modify the serialized structures to induce memory corruption, leading to arbitrary code execution. This is caused by Incorrect Use of Privileged APIs.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.43%

34.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Arm	Mbed Tls	>= 2.19.0, < 3.6.6
Trustedfirmware	Mbed Tls	4.0.0

References

https://mbed-tls.readthedocs.io/en/latest/security-advisories/Vendor Advisory
https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-serialized-data/Vendor Advisory

Timeline

Published: Apr 2, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-34877?

How severe is CVE-2026-34877?

CVE-2026-34877 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.43% probability of exploitation in the next 30 days.

How do I fix CVE-2026-34877?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-34877?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST