---
id: CVE-2025-9231
title: Timing side-channel in SM2 algorithm on 64 bit ARM
summary: >-
  Issue summary: A timing side-channel which could potentially allow remote

  recovery of the private key exists in the SM2 algorithm implementation on 64
  bit

  ARM platforms.


  Impact summary: A timing side-channel in SM2 signature computation…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'
cvssSource: adp
cwe:
  - CWE-385
vendor: OpenSSL
product: OpenSSL
affected:
  - OpenSSL >= 3.5.0 < 3.5.4
  - OpenSSL >= 3.4.0 < 3.4.3
  - OpenSSL >= 3.3.0 < 3.3.5
  - OpenSSL >= 3.2.0 < 3.2.6
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2025-09-30T19:27:45.704985Z'
published: '2025-09-30'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T21:45:40.974Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-9231'
references:
  - url: 'https://openssl-library.org/news/secadv/20250930.txt'
    label: OpenSSL Advisory
  - url: >-
      https://github.com/openssl/openssl/commit/fc47a2ec078912b3e914fab5734535e76c4820c2
    label: 3.5.4 git commit
  - url: >-
      https://github.com/openssl/openssl/commit/eed5adc9f969d77c94f213767acbb41ff923b6f4
    label: 3.4.3 git commit
  - url: >-
      https://github.com/openssl/openssl/commit/567f64386e43683888212226824b6a179885a0fe
    label: 3.3.5 git commit
  - url: >-
      https://github.com/openssl/openssl/commit/cba616c26ac8e7b37de5e77762e505ba5ca51698
    label: 3.2.6 git commit
tags:
  - cve.org
epss: 0.0147
epssPercentile: 0.73935
ingestedAt: '2026-11-06T22:04:56.310Z'
---

## Overview

Issue summary: A timing side-channel which could potentially allow remote
recovery of the private key exists in the SM2 algorithm implementation on 64 bit
ARM platforms.

Impact summary: A timing side-channel in SM2 signature computations on 64 bit
ARM platforms could allow recovering the private key by an attacker..

While remote key recovery over a network was not attempted by the reporter,
timing measurements revealed a timing signal which may allow such an attack.

OpenSSL does not directly support certificates with SM2 keys in TLS, and so
this CVE is not relevant in most TLS contexts.  However, given that it is
possible to add support for such certificates via a custom provider, coupled
with the fact that in such a custom provider context the private key may be
recoverable via remote timing measurements, we consider this to be a Moderate
severity issue.

The FIPS modules in 3.5, 3.4, 3.3, 3.2, 3.1 and 3.0 are not affected by this
issue, as SM2 is not an approved algorithm.

## Affected

- `OpenSSL >= 3.5.0 < 3.5.4`
- `OpenSSL >= 3.4.0 < 3.4.3`
- `OpenSSL >= 3.3.0 < 3.3.5`
- `OpenSSL >= 3.2.0 < 3.2.6`

## Remediation

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