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.
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.
Published:
2026-09-29
Score:
n/a
EPSS:
n/a
KEV:
No
Impact:
n/a
Action:
n/a
Analysis
Analysis and contextual insights are available on OpenCVE Cloud.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| OpenSSL | OpenSSL | unaffected |
|
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No data.
No data available yet.
Remediation
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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Advisories
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References
History
Tue, 29 Sep 2026 15:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Timing Side-Channel in Scalar Multiplication for Non-NIST EC Curves | |
| Weaknesses | CWE-208 | |
| References |
|
|
Subscriptions
No data.
MITRE
Status: PUBLISHED
Assigner: openssl
Published:
Updated: 2026-09-29T15:32:15.075Z
Reserved: 2026-06-16T10:18:08.635Z
Link: CVE-2026-54872
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
-
CWE-208
Observable Timing Discrepancy