---
id: CVE-2026-25832
title: >-
  In Mbed TLS 3.6.x before 3.6.7 and 4.1.x before 4.1.2, the TLS 1.3 client
  accepts HelloRetryRequest selecting an unadvertised group.
summary: >-
  In Mbed TLS 3.6.x before 3.6.7 and 4.1.x before 4.1.2, the TLS 1.3 client
  accepts HelloRetryRequest selecting an unadvertised group.
severity: low
cvss: 3.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'
cwe:
  - CWE-669
vendor: TrustedFirmware
product: Mbed TLS
affected:
  - mbed_tls >= 3.5.0 < 3.6.7
  - mbed_tls >= 4.0.0 < 4.1.2
published: '2026-09-14'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T19:56:19.073'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-25832'
references:
  - url: 'https://mbed-tls.readthedocs.io/en/latest/security-advisories/'
    label: cve@mitre.org
  - url: >-
      https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-07-tls13-hrr-unadvertised-group/
    label: cve@mitre.org
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25832.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-25832'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-25832'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00218
epssPercentile: 0.12512
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-14T15:59:33.992126Z'
ingestedAt: '2026-09-14T15:23:07.465Z'
---

## Overview

In Mbed TLS 3.6.x before 3.6.7 and 4.1.x before 4.1.2, the TLS 1.3 client accepts HelloRetryRequest selecting an unadvertised group.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25832.json)