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

> Attackers can recover private keys from ECDSA/SM2 signatures on non-NIST curves via timing side-channels in OpenSSL's generic scalar multiplication.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Sep 2026
- **Updated:** 29 Sep 2026
- **Also known as:** ALPINE-CVE-2026-54872, AZL-105360, AZL-105450, AZL-105480, AZL-105504, AZL-105573, AZL-105621, AZL-105708, AZL-105843, AZL-105858, BELL-CVE-2026-54872, CLEANSTART-2026-KH74871, DEBIAN-CVE-2026-54872, ECHO-1163-5842-15ed, GHSA-rv5h-5m9v-ccwc, MINI-r8j8-f868-pg45, UBUNTU-CVE-2026-54872

## What is CVE-2026-54872?

CVE-2026-54872 is a low-severity vulnerability in Openssl Openssl, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-208 (Observable Timing Discrepancy)

## Which versions are affected by CVE-2026-54872?

It affects 1 product.


Products: Openssl Openssl.

## How do I fix CVE-2026-54872?

Apply the vendor's patch.

## Is CVE-2026-54872 being exploited?

There is no known exploitation of CVE-2026-54872 in the wild and no public exploit code.

## Other vulnerabilities in Openssl Openssl

- [CVE-2009-3245](https://insights.sbomify.com/CVE-2009-3245/): Null dereference in n/a (critical 10.0)
- [CVE-2006-3738](https://insights.sbomify.com/CVE-2006-3738/): Memory corruption in n/a (critical 10.0)
- [CVE-2026-63073](https://insights.sbomify.com/CVE-2026-63073/): Untrusted Sender DN Used as Format String in CMP Response Validation (critical 9.8)
- [CVE-2016-6309](https://insights.sbomify.com/CVE-2016-6309/): Use after free in n/a (critical 9.8)
- [CVE-2016-0799](https://insights.sbomify.com/CVE-2016-0799/): Integer overflow in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54872 and fix it if it is affected.

What it is: CVE-2026-54872 is a low-severity vulnerability in Openssl Openssl, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-54872 in the wild and no public exploit code.

Affected product: Openssl Openssl. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-54872/ (Markdown: https://insights.sbomify.com/CVE-2026-54872/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54872
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54872
- OSV: https://osv.dev/vulnerability/CVE-2026-54872

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54872/
Summaries are generated and may contain mistakes; the official description above is the record.