CVE-2026-54872 Affecting openssl package, versions <3.6.5-1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published30 Sept 2026
- disclosed29 Sept 2026
Introduced: 29 Sep 2026
NewCVE-2026-54872 (opens in a new tab)How to fix?
Upgrade Debian:unstable openssl to version 3.6.5-1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream openssl package and not the openssl package as distributed by Debian.
See How to fix? for Debian:unstable relevant fixed versions and status.
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.
References
- https://security-tracker.debian.org/tracker/CVE-2026-54872
- https://github.com/openssl/openssl/commit/1a5bee8dc57430a2be69cd1ffe7fec6a62f4f179
- https://github.com/openssl/openssl/commit/3f7e1363dccec6f7732bb9e9fa471bb6e4aa68cb
- https://github.com/openssl/openssl/commit/7d83bc7764999dfd91b83b4f0815b45390422afd
- https://github.com/openssl/openssl/commit/8166827a78aad164a07aa86dea2b425403ced471
- https://openssl-library.org/news/secadv/20260929.txt