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3.7

OpenSSL on ARM64/RISC-V can leak private keys

CVE-2026-54875 · published 20 days ago
Summary

OpenSSL versions 4.0, 3.6, 3.5 and 3.4 running on ARM64 or RISC‑V processors use a special calculation that takes slightly different amounts of time depending on the secret key. An attacker who can watch how long a signing or decryption operation takes, or see which memory areas are accessed, could infer parts of that key. Update OpenSSL to the latest patched releases (4.0.3, 3.6.5, 3.5.9, or 3.4.8) to remove the weakness.

What to do
  • Update canonical openssl to version 3.5.5-1ubuntu3.6.
  • Update alpine openssl to version 3.3.7-r2.
  • Update bellsoft openssl to version 3.5.9-r0.
  • Update openssl to version 3.5.9-r0.
  • Update debian openssl to version 3.5.7-1~deb13u3.
  • Update debian openssl to version 3.6.5-1.
  • Update openssl to version 3.3.7-r2.
Affected software
Ecosystem VendorProductAffected versions
Ubuntu:26.04:LTS canonical edk2 All versions
Ubuntu:26.04:LTS canonical edk2-hwe All versions
– openssl openssl < 4.0.3
>= 3.4.0, < 3.4.8
>= 3.5.0, < 3.5.9
>= 3.6.0, < 3.6.5
>= 4.0.0, < 4.0.3
Debian:13 debian openssl < 3.5.7-1~deb13u3
Fix: upgrade to 3.5.7-1~deb13u3
Ubuntu:Pro:22.04:LTS canonical nodejs All versions
Ubuntu:26.04:LTS canonical openssl < 3.5.5-1ubuntu3.6
Fix: upgrade to 3.5.5-1ubuntu3.6
Alpine:v3.21 alpine openssl < 3.3.7-r2
Fix: upgrade to 3.3.7-r2
Alpaquita:25 bellsoft openssl >= 3.5.0-r0, < 3.5.9-r0
Fix: upgrade to 3.5.9-r0
BellSoft Hardened Containers:25 – openssl >= 3.5.0-r0, < 3.5.9-r0
Fix: upgrade to 3.5.9-r0
Debian:14 debian openssl < 3.6.5-1
Fix: upgrade to 3.6.5-1
Alpine:v3.21 – openssl >= 3.4.0, < 3.3.7-r2
Fix: upgrade to 3.3.7-r2
Original advisory text
Non-Constant-Time SM2 Scalar Multiplication on ARM64 and RISC-V
Issue summary: A non-constant-time optimized implementation of scalar
point multiplication is used for SM2 private key operations on ARM64 and
RISC-V platforms.

Impact summary: An attacker able to measure the time taken by, or to observe
the cache-line access pattern of SM2 signing or decryption on an affected
platform can learn information about the secret scalar.

CWE: CWE-208: Observable Timing Discrepancy

Description: On ARM64 and RISC-V processors, the SM2 curve uses an optimized
scalar multiplication implementation whose conditional branches and table
look ups are chosen according to the bits of the secret scalar. The execution
time and the cache-access pattern therefore depend on the long-term private
key (during SM2 decryption) or the per-signature nonce (during SM2 signature
generation), forming a timing and cache side-channel.

FIPS Impact: no
SM2 is not a FIPS algorithm and the optimized SM2 implementation is not part
of the FIPS module.

OpenSSL 4.0, 3.6, 3.5 and 3.4 are vulnerable to this issue on AArch64 and
RISC-V.

OpenSSL 3.0, 1.1.1 and 1.0.2 are not affected by this issue.

OpenSSL 4.0 users should upgrade to OpenSSL 4.0.3.
OpenSSL 3.6 users should upgrade to OpenSSL 3.6.5.
OpenSSL 3.5 users should upgrade to OpenSSL 3.5.9.
OpenSSL 3.4 users should upgrade to OpenSSL 3.4.8.

This issue was reported on 2 May 2026 by Abhinav Agarwal.
It was independently reported on 6 June 2026 by Feng Xue.
The fix was developed by Igor Ustinov.

-- cut (non-publishing metadata for internal use) --
Reported by: Abhinav Agarwal, Feng Xue
Fixed by: Igor Ustinov
References
Fix within
Internet-facing 60 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit
  • Gives an attacker partial control
Severity
3.7 Low
Exploitation
<1% chance of attack within 30 days
Type
CWE-208Observable Timing Discrepancy
Timeline
Published29 Sep 2026
Updated19 Oct 2026
First seen29 Sep 2026
Sources
CVE-2026-54875 · NVD
CVE-2026-54875 · MITRE
DEBIAN-CVE-2026-54875 · OSV
UBUNTU-CVE-2026-54875 · OSV
ALPINE-CVE-2026-54875 · OSV
CVE-2026-54875 · OSV
BELL-CVE-2026-54875 · OSV
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