CVE-2026-77696
Full vulnerability record from the local CVENow database.
Description
Issue 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.
Severity
LOW
CVSS score
3.7
(v3.1)
Vulnerability status
Modified
Source identifier
Published
2026-09-29 16:17:11.493000
Last modified
2026-11-10 13:19:40.053000
View original CVE JSON
{
"id": "CVE-2026-77696",
"sourceIdentifier": "[email protected]",
"published": "2026-09-29T16:17:11.493",
"lastModified": "2026-11-10T13:19:40.053",
"vulnStatus": "Modified",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Issue summary: SM2 signature generation uses non-constant-time arithmetic\non secret values, forming a timing side-channel.\n\nImpact summary: An attacker able to measure SM2 signing times may learn\ninformation about the per-signature secret nonce, which over many signatures\ncan, via a lattice / Hidden Number Problem attack, lead to recovery of the\nprivate key.\n\nCWE: CWE-208: Observable Timing Discrepancy\n\nDescription: SM2 signature generation computes the signature value using\nvariable-time BIGNUM operations on the secret nonce and the private key, so\nthe time taken to produce an SM2 signature depends on these secret values,\nforming a timing side-channel.\n\nApplications performing SM2 signature generation are affected on all\nplatforms.\n\nFIPS Impact: no\nSM2 is not a FIPS algorithm."
}
],
"affected": [
{
"source": "[email protected]",
"affectedData": [
{
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"product": "OpenSSL",
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"metrics": {
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"baseScore": 3.7,
"baseSeverity": "LOW",
"attackVector": "NETWORK",
"attackComplexity": "HIGH",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"availabilityImpact": "NONE"
},
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"ssvcV203": [
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"ssvcData": {
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"id": "CVE-2026-77696",
"options": [
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{
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{
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"role": "CISA Coordinator",
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"weaknesses": [
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"source": "[email protected]",
"type": "Secondary",
"description": [
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"configurations": [
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"source": "[email protected]",
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{
"url": "https://cert-portal.siemens.com/productcert/html/ssa-457936.html",
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}