CVE-2026-54872

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-29 16:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-08 01:19 UTC Last updatedMost recent change to the record

Details

Published

2026-09-29 16:17 UTC

Last modified

2026-10-08 01:19 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-208

Record status

Analyzed

Affected

• OpenSSL < 1.0.2zs
• OpenSSL < 1.1.1zj
• OpenSSL < 3.0.23
• OpenSSL < 3.4.8
• OpenSSL < 3.5.9
• OpenSSL < 3.6.5
• OpenSSL < 4.0.3

Attack profile CVSS 3.1 · 3.7

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None