CVE-2025-9231Network attack vector

Private-key disclosure via variable-time SM2 inversion

Published Sep 30, 2025 · Updated Sep 30, 2025

Timing side-channel in SM2 signing in OpenSSL allows attackers to measure private-key-dependent execution time on 64-bit ARM platforms. The crypto/ec/ecp_sm2p256.c method dispatches signature inversion through a variable-time modular inverse instead of the constant-time fallback, making signature duration depend on secret values. Remote recovery has not been demonstrated; TLS exposure requires a custom provider for SM2 certificates, and the listed FIPS modules are unaffected.

CVSS severity6.5
Medium
EPSS probability2.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Timing side-channel in SM2 signing in OpenSSL allows attackers to measure private-key-dependent execution time on 64-bit ARM platforms. The crypto/ec/ecp_sm2p256.c method dispatches signature inversion through a variable-time modular inverse instead of the constant-time fallback, making signature duration depend on secret values. Remote recovery has not been demonstrated; TLS exposure requires a custom provider for SM2 certificates, and the listed FIPS modules are unaffected.

The record

CVE
CVE-2025-9231
Published
Sep 30, 2025
Updated
Sep 30, 2025
Vendor
OpenSSL Project
Product
OpenSSL
Classifications
CWE-385
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 30, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 30, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.2.0 <3.2.6
  2. Affected versionversion=3.3.0 <3.3.5
  3. Affected versionversion=3.4.0 <3.4.3
  4. Affected versionversion=3.5.0 <3.5.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenSSL Project · OpenSSLversion=3.2.0 <3.2.6; version=3.3.0 <3.3.5; version=3.4.0 <3.4.3; version=3.5.0 <3.5.4

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-385Covert Timing Channel

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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