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CVE-2026-54872

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

Products / packages OpenSSL · Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) · Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) · 3 more

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Severity and exploitation

Not in CISA KEV

KEV coverage does not rule out exploitation.

KEV checked 15/11/2026, 00:55:33 UTC
CISA-ADP · CVSS:3.1 · 3.7
Assessment vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Severity

low3.7

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Fix status not established

No structured fix or guidance is available here. Check the latest publisher advisory.

What this means

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.

Source excerpt · openssl

Attack conditions

The leak is very small; observing it requires a large number of measurements.

Excerpt from the original source description below.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

OpenSSL · openssl

OpenSSL

7 ranges
openssl version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

4.0.0 → before 4.0.3

semver versions

3.6.0 → before 3.6.5

semver versions

3.5.0 → before 3.5.9

semver versions

3.4.0 → before 3.4.8

semver versions

3.0.0 → before 3.0.23

semver versions

1.1.1 → before 1.1.1zj

custom versions

1.0.2 → before 1.0.2zs

custom versions

unaffected

unknown

Other versions: unaffected

Siemens · siemens-SADP

SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)

1 range
siemens-SADP version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

V3.1.7 → before *

custom versions

unaffected

unknown

Other versions: unknown

Siemens · siemens-SADP

SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)

1 range
siemens-SADP version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

V3.1.7 → before *

custom versions

unaffected

unknown

Other versions: unknown

Siemens · siemens-SADP

SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)

1 range
siemens-SADP version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

V3.1.7 → before *

custom versions

unaffected

unknown

Other versions: unknown

Siemens · siemens-SADP

SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)

1 range
siemens-SADP version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

V3.1.7 → before *

custom versions

unaffected

unknown

Other versions: unknown

Siemens · siemens-SADP

SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)

1 range
siemens-SADP version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

V3.1.7 → before *

custom versions

unaffected

unknown

Other versions: unknown

Automatic dependency matching is unavailable for this record. Use the product evidence and publisher’s instructions to check your installation.

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

No structured fix or remediation guidance is available here. Check the full source description and vendor’s latest advisory for a patch or workaround; do not assume another version is safe.

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher 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.

References

6 sources
openssl-library.org/news/secadv/20260929.txt
Vendor advisoryopenssl
openssl/openssl · commit 8166827
Patchopenssl
openssl/openssl · commit 1a5bee8
Patchopenssl
openssl/openssl · commit 3f7e136
Patchopenssl
openssl/openssl · commit 7d83bc7
Patchopenssl
cert-portal.siemens.com/productcert/html/ssa-457936.html
Source referencesiemens-SADP

Inside the record

Evidence available

Package identity · not supplied
Version evidence
Remediation guidance · not supplied
Weakness classification
Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-54872

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-208 ↗

CWE-208 Observable Timing Discrepancy

openssl

Related →
Contributing organizations · 3
openssl

Assigning organization

2026-09-29
CISA-ADP

Additional data publisher

2026-09-29
siemens-SADP

Additional data publisher

2026-11-10

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes
No substantive changes have been recorded here yet. History starts when cve.new observes a change after tracking is enabled; earlier edits are not reconstructed.

Large field values are marked as truncated previews. Original source snapshots remain retained.