# CVE-2018-0735: Timing attack against ECDSA signature generation

> An attacker can recover private keys via timing side-channel attacks during ECDSA signature generation in OpenSSL.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/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 Oct 2018
- **Updated:** 8 Oct 2026
- **Also known as:** ALPINE-CVE-2018-0735, CLEANSTART-2026-JO42932, CLEANSTART-2026-YZ01964, DEBIAN-CVE-2018-0735, GHSA-4fhm-44hf-3465, UBUNTU-CVE-2018-0735

## What is CVE-2018-0735?

CVE-2018-0735 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 29 Oct 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The OpenSSL ECDSA signature algorithm has been shown to be vulnerable to a timing side channel attack. An attacker could use variations in the signing algorithm to recover the private key. Fixed in OpenSSL 1.1.0j (Affected 1.1.0-1.1.0i). Fixed in OpenSSL 1.1.1a (Affected 1.1.1).

Weakness: CWE-327 (Use of a Broken or Risky Cryptographic Algorithm)

## Which versions are affected by CVE-2018-0735?

It affects 22 products.


Products: Canonical Ubuntu Linux, Debian Debian Linux, Netapp Cloud Backup, Netapp Cn1610 Firmware, Netapp Element Software, Netapp Oncommand Unified Manager, Netapp Santricity Smi-S Provider, Netapp Smi-S Provider, Netapp Snapdrive, Netapp Steelstore, Nodejs Node.js, Openssl Openssl, Oracle Api Gateway, Oracle Application Server, Oracle Enterprise Manager Base Platform, Oracle Enterprise Manager Ops Center, Oracle Mysql, Oracle Peoplesoft Enterprise Peopletools, Oracle Primavera P6 Enterprise Project Portfolio Management, Oracle Secure Global Desktop and 2 more.

## How do I fix CVE-2018-0735?

Upgrade to a fixed version.

## Is CVE-2018-0735 being exploited?

There is no known exploitation of CVE-2018-0735 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-0735 and fix it if it is affected.

What it is: CVE-2018-0735 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 29 Oct 2018. 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-2018-0735 in the wild and no public exploit code.

Affected product: Canonical Ubuntu Linux. 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-2018-0735/ (Markdown: https://insights.sbomify.com/CVE-2018-0735/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-0735
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-0735
- OSV: https://osv.dev/vulnerability/CVE-2018-0735

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From sbomify Insights: https://insights.sbomify.com/CVE-2018-0735/
Summaries are generated and may contain mistakes; the official description above is the record.