CVE-2026-54872 - Timing Side-Channel in Scalar Multiplication for Non-NIST EC Curves

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MEDIUM

Timing Side-Channel in Scalar Multiplication for Non-NIST EC Curves

Published Sep 29, 2026

5.9

MEDIUM

CVSS 3.1

EPSS 0.26%

Description

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.

Affected products

Vendor OpenSSL Product OpenSSL Default
unaffected
- Version
  1.0.2
  Status
  affected
  Constraints
  <1.0.2zs
- Version
  1.1.1
  Status
  affected
  Constraints
  <1.1.1zj
- Version
  3.0.0
  Status
  affected
  Constraints
  <3.0.23
- 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
1.0.2	affected	<1.0.2zs
1.1.1	affected	<1.1.1zj
3.0.0	affected	<3.0.23
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 (9)

Link	Providers	Tags
https://access.redhat.com/security/cve/CVE-2026-54872		Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2543250		Issue Tracking
https://github.com/openssl/openssl/commit/1a5bee8dc57430a2be69cd1ffe7fec6a62f4f179		patch
https://github.com/openssl/openssl/commit/3f7e1363dccec6f7732bb9e9fa471bb6e4aa68cb		patch
https://github.com/openssl/openssl/commit/7d83bc7764999dfd91b83b4f0815b45390422afd		patch
https://github.com/openssl/openssl/commit/8166827a78aad164a07aa86dea2b425403ced471		patch
https://nvd.nist.gov/vuln/detail/CVE-2026-54872
https://openssl-library.org/news/secadv/20260929.txt		vendor-advisory
https://www.cve.org/CVERecord?id=CVE-2026-54872