Timing Side-Channel in SM2 Signature Generation

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-77696
StatePUBLISHED
Assigneropenssl
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-29 16:17:11 UTC
Updated2026-09-29 21:27:41 UTC
DescriptionIssue summary: SM2 signature generation uses non-constant-time arithmetic on secret values, forming a timing side-channel. Impact summary: An attacker able to measure SM2 signing times may learn information about the per-signature secret nonce, which over many signatures can, via a lattice / Hidden Number Problem attack, lead to recovery of the private key. CWE: CWE-208: Observable Timing Discrepancy Description: SM2 signature generation computes the signature value using variable-time BIGNUM operations on the secret nonce and the private key, so the time taken to produce an SM2 signature depends on these secret values, forming a timing side-channel. Applications performing SM2 signature generation are affected on all platforms. FIPS Impact: no SM2 is not a FIPS algorithm.

Risk And Classification

Primary CVSS: v3.1 3.7 LOW from ADP

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

Problem Types: CWE-208 | CWE-208 CWE-208 Observable Timing Discrepancy

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA OpenSSL OpenSSL affected 4.0.0 4.0.3 semver Not specified
CNA OpenSSL OpenSSL affected 3.6.0 3.6.5 semver Not specified
CNA OpenSSL OpenSSL affected 3.5.0 3.5.9 semver Not specified
CNA OpenSSL OpenSSL affected 3.4.0 3.4.8 semver Not specified
CNA OpenSSL OpenSSL affected 3.0.0 3.0.23 semver Not specified
CNA OpenSSL OpenSSL affected 1.1.1 1.1.1zj custom Not specified

References

ReferenceSourceLinkTags
github.com/openssl/openssl/commit/20b20628d39b2dcc4677194bd68c7c060fa598cb [email protected] github.com
github.com/openssl/openssl/commit/6b90445a56b99a328ac1feba058abf976504f440 [email protected] github.com
github.com/openssl/openssl/commit/1c4aed808a7aea32d2d013049c2e0d9fef164fc9 [email protected] github.com
openssl-library.org/news/secadv/20260929.txt [email protected] openssl-library.org
github.com/openssl/openssl/commit/419f5cb519721dceed393dbc524d79e487c72e64 [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Vladimir Tokarev (en)

CNA: Igor Ustinov (en)

CNA: Viktor Dukhovni (en)

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report