Timing Side-Channel in Scalar Multiplication for Non-NIST EC Curves
Summary
| CVE | CVE-2026-54872 |
|---|---|
| State | PUBLISHED |
| Assigner | openssl |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-29 16:17:08 UTC |
| Updated | 2026-09-29 21:27:41 UTC |
| Description | Issue summary: The generic elliptic-curve scalar multiplication used for ECDSA and SM2 signature operations with curves that do not have a dedicated implementation leaks information about the secret nonce through timing. Impact summary: An attacker able to measure 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: The generic elliptic-curve scalar multiplication used for curves that do not have a dedicated constant-time implementation pads the secret scalar with non-constant-time BIGNUM operations, so the time taken depends on the value of the secret scalar derived from the ECDSA and SM2 nonce. The leak is very small; observing it requires a large number of measurements. The effect is largest for curves whose group order lies on a machine-word boundary, such as brainpoolP384r1. Applications using ECDSA signing over the Brainpool and other generic prime curves, and SM2 signing on platforms that use the generic implementation, are vulnerable to this issue. The NIST curves P-256, P-384 and P-521 use dedicated constant-time implementations and are not affected. FIPS Impact: no The FIPS modules are not affected: the approved NIST curves used in the FIPS provider have dedicated constant-time implementations and do not use the affected code path. |
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
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | DECLARED | 3.7 | LOW | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 3.7 | LOW | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
HighPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
LowIntegrity
NoneAvailability
NoneCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| 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 |
| CNA | OpenSSL | OpenSSL | affected 1.0.2 1.0.2zs custom | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/openssl/openssl/commit/3f7e1363dccec6f7732bb9e9fa471bb6e4aa68cb | [email protected] | github.com | |
| github.com/openssl/openssl/commit/7d83bc7764999dfd91b83b4f0815b45390422afd | [email protected] | github.com | |
| github.com/openssl/openssl/commit/1a5bee8dc57430a2be69cd1ffe7fec6a62f4f179 | [email protected] | github.com | |
| openssl-library.org/news/secadv/20260929.txt | [email protected] | openssl-library.org | |
| github.com/openssl/openssl/commit/8166827a78aad164a07aa86dea2b425403ced471 | [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: Igor Ustinov (en)
There are currently no legacy QID mappings associated with this CVE.