CVE-2026-54875: OpenSSL SM2 timing side-channel in scalar multiplication on ARM64 and RISC-V

CVE-2026-54875 · Severity: info · Published 2026-09-29

OpenSSL's implementation of SM2 cryptographic operations leaks information about secret keys through timing and cache access patterns on ARM64 and RISC-V processors. An attacker who can measure execution time or monitor cache behavior during SM2 signing or decryption could potentially recover portions of the private key, compromising the security of encrypted communications and digital signatures relying on SM2.

Technologies: OpenSSL. Vendors: OpenSSL.

Quick answers

Is CVE-2026-54875 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-54875 being exploited in the wild.
How severe is CVE-2026-54875?
Informational severity, published 29 September 2026.
Which products and versions are affected?
OpenSSL 3.4.0 through 3.4.7, 3.5.0 through 3.5.8, 3.6.0 through 3.6.4, 4.0.0 through 4.0.2.
Is there a fix for CVE-2026-54875?
A patch was published on 2026-09-29: Fixed in OpenSSL 4.0.3, 3.6.5, 3.5.9, and 3.4.8 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-54875 attacked?
It is attacked with local access or from the adjacent network, in a software library.
Am I affected by CVE-2026-54875?
Check whether you run OpenSSL at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The SM2 scalar multiplication implementation on ARM64 and RISC-V uses conditional branches and table lookups that vary with the secret scalar bits, creating a timing and cache side-channel (CWE-208). Exploitation requires the ability to measure execution time or observe cache-line access patterns during SM2 decryption or signature generation. The non-constant-time implementation affects OpenSSL versions 3.4 through 4.0 on these architectures only, and fixes are available in 4.0.3, 3.6.5, 3.5.9, and 3.4.8.

Affected products

  • OpenSSL OpenSSL 3.4.0 through 3.4.7, 3.5.0 through 3.5.8, 3.6.0 through 3.6.4, 4.0.0 through 4.0.2

Timeline

  • 2026-05-02: disclosed: Reported by Abhinav Agarwal
  • 2026-06-06: disclosed: Independently reported by Feng Xue
  • 2026-09-29: patched: Fixed in OpenSSL 4.0.3, 3.6.5, 3.5.9, and 3.4.8

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