CVE-2026-54875 - Non-Constant-Time SM2 Scalar Multiplication on ARM64 and RISC-V

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MEDIUM

Non-Constant-Time SM2 Scalar Multiplication on ARM64 and RISC-V

Published Sep 29, 2026

4.7

MEDIUM

CVSS 3.1

EPSS 0.29%

Description

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

Affected products

Vendor OpenSSL Product OpenSSL Default
unaffected
- Version
  3.4.0
  Status
  affected
  Constraints
  <3.4.8
- Version
  3.5.0
  Status
  affected
  Constraints
  <3.5.9
- Version
  3.6.0
  Status
  affected
  Constraints
  <3.6.5
- Version
  4.0.0
  Status
  affected
  Constraints
  <4.0.3

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

OpenSSL

unaffected

Version	Status	Constraints
3.4.0	affected	<3.4.8
3.5.0	affected	<3.5.9
3.6.0	affected	<3.6.5
4.0.0	affected	<4.0.3

Red Hat Hardened Images

openssl-main-3.5.9-0.1.hum1

Fixed · RHSA-2026:74162
Red Hat Hardened Images

openssl3-main-3.5.9-0.1.hum1

Fixed · RHSA-2026:74166
Red Hat Developer Hub

rhdh/rhdh-hub-rhel9

Fix deferred
Red Hat Enterprise Linux 10

edk2

Fix deferred
Red Hat Enterprise Linux 10

openssl

Affected
Red Hat Enterprise Linux 10

shim

Fix deferred
Red Hat Enterprise Linux 10

shim-unsigned-aarch64

Fix deferred
Red Hat Enterprise Linux 10

shim-unsigned-x64

Fix deferred
Red Hat Enterprise Linux 6

openssl

Out of support scope
Red Hat Enterprise Linux 7

openssl

Fix deferred
Red Hat Enterprise Linux 7

ovmf

Fix deferred
Red Hat Enterprise Linux 7

shim-signed

Fix deferred
Red Hat Enterprise Linux 8

compat-openssl10

Fix deferred
Red Hat Enterprise Linux 8

edk2

Fix deferred
Red Hat Enterprise Linux 8

mingw-openssl

Fix deferred
Red Hat Enterprise Linux 8

openssl

Fix deferred
Red Hat Enterprise Linux 8

shim

Fix deferred
Red Hat Enterprise Linux 8

shim-unsigned-aarch64

Fix deferred
Red Hat Enterprise Linux 8

shim-unsigned-x64

Fix deferred
Red Hat Enterprise Linux 9

compat-openssl11

Fix deferred
Red Hat Enterprise Linux 9

edk2

Fix deferred
Red Hat Enterprise Linux 9

openssl

Affected
Red Hat Enterprise Linux 9

shim

Fix deferred
Red Hat Enterprise Linux 9

shim-unsigned-aarch64

Fix deferred
Red Hat Enterprise Linux 9

shim-unsigned-x64

Fix deferred
Red Hat Hardened Images

unbound

Not affected
Red Hat JBoss Core Services

jbcs-httpd24-openssl

Fix deferred
Red Hat OpenShift Container Platform 4

openshift/ose-rhel-coreos-8

Fix deferred
Red Hat OpenShift Container Platform 4

openshift/ose-rhel-coreos-9

Fix deferred
Red Hat Satellite 6

openvox-agent

Fix deferred
Red Hat Satellite 6

puppet-agent

Fix deferred

Product	Package	State	Advisory
Red Hat Hardened Images	openssl-main-3.5.9-0.1.hum1	Fixed	RHSA-2026:74162
Red Hat Hardened Images	openssl3-main-3.5.9-0.1.hum1	Fixed	RHSA-2026:74166
Red Hat Developer Hub	rhdh/rhdh-hub-rhel9	Fix deferred	n/a
Red Hat Enterprise Linux 10	edk2	Fix deferred	n/a
Red Hat Enterprise Linux 10	openssl	Affected	n/a
Red Hat Enterprise Linux 10	shim	Fix deferred	n/a
Red Hat Enterprise Linux 10	shim-unsigned-aarch64	Fix deferred	n/a
Red Hat Enterprise Linux 10	shim-unsigned-x64	Fix deferred	n/a
Red Hat Enterprise Linux 6	openssl	Out of support scope	n/a
Red Hat Enterprise Linux 7	openssl	Fix deferred	n/a
Red Hat Enterprise Linux 7	ovmf	Fix deferred	n/a
Red Hat Enterprise Linux 7	shim-signed	Fix deferred	n/a
Red Hat Enterprise Linux 8	compat-openssl10	Fix deferred	n/a
Red Hat Enterprise Linux 8	edk2	Fix deferred	n/a
Red Hat Enterprise Linux 8	mingw-openssl	Fix deferred	n/a
Red Hat Enterprise Linux 8	openssl	Fix deferred	n/a
Red Hat Enterprise Linux 8	shim	Fix deferred	n/a
Red Hat Enterprise Linux 8	shim-unsigned-aarch64	Fix deferred	n/a
Red Hat Enterprise Linux 8	shim-unsigned-x64	Fix deferred	n/a
Red Hat Enterprise Linux 9	compat-openssl11	Fix deferred	n/a
Red Hat Enterprise Linux 9	edk2	Fix deferred	n/a
Red Hat Enterprise Linux 9	openssl	Affected	n/a
Red Hat Enterprise Linux 9	shim	Fix deferred	n/a
Red Hat Enterprise Linux 9	shim-unsigned-aarch64	Fix deferred	n/a
Red Hat Enterprise Linux 9	shim-unsigned-x64	Fix deferred	n/a
Red Hat Hardened Images	unbound	Not affected	n/a
Red Hat JBoss Core Services	jbcs-httpd24-openssl	Fix deferred	n/a
Red Hat OpenShift Container Platform 4	openshift/ose-rhel-coreos-8	Fix deferred	n/a
Red Hat OpenShift Container Platform 4	openshift/ose-rhel-coreos-9	Fix deferred	n/a
Red Hat Satellite 6	openvox-agent	Fix deferred	n/a
Red Hat Satellite 6	puppet-agent	Fix deferred	n/a

Remediation

No remediation recorded yet.

Weaknesses (1)

CWE-208

References (10)

Link	Providers	Tags
https://access.redhat.com/security/cve/CVE-2026-54875		Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2543256		Issue Tracking
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-89006		Advisory
https://github.com/openssl/openssl/commit/3f01bbc28f7e08211fcdc797fd43816504f94257		patch
https://github.com/openssl/openssl/commit/469f3e42629f4a0b5631796e20c66c92c138a3e8		patch
https://github.com/openssl/openssl/commit/9794ed473764839275cb701b4850f3c24d929c28		patch
https://github.com/openssl/openssl/commit/dddad955d5ff3e9507619cf4e0f13e9988e2197c		patch
https://nvd.nist.gov/vuln/detail/CVE-2026-54875
https://openssl-library.org/news/secadv/20260929.txt		vendor-advisory
https://www.cve.org/CVERecord?id=CVE-2026-54875