CVE-2026-54872Timing Side-Channel in Scalar Multiplication for Non-NIST EC Curves
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 3.7 LOW (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
- Weakness (CWE)
- CWE-208
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- openssl
- NVD analysis
- Analyzed
- Record last updated
- Sep 29, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
OpenSSL OpenSSL openssl:openssl (from the name) | from 4.0.0 before 4.0.3; from 3.6.0 before 3.6.5; from 3.5.0 before 3.5.9; from 3.4.0 before 3.4.8; from 3.0.0 before 3.0.23; from 1.1.1 before 1.1.1zj; from 1.0.2 before 1.0.2zs | CNA record |
openssl openssl openssl:openssl | from 1.0.2 before 1.0.2zs; from 1.1.1 before 1.1.1zj; from 3.0.0 before 3.0.23; from 3.4.0 before 3.4.8; from 3.5.0 before 3.5.9; from 3.6.0 before 3.6.5; from 4.0.0 before 4.0.3 | NVD |
References
- https://openssl-library.org/news/secadv/20260929.txtvendor-advisory
- https://github.com/openssl/openssl/commit/8166827a78aad164a07aa86dea2b425403ced471patch
- https://github.com/openssl/openssl/commit/1a5bee8dc57430a2be69cd1ffe7fec6a62f4f179patch
- https://github.com/openssl/openssl/commit/3f7e1363dccec6f7732bb9e9fa471bb6e4aa68cbpatch
- https://github.com/openssl/openssl/commit/7d83bc7764999dfd91b83b4f0815b45390422afdpatch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.