# CVE-2019-1551: rsaz_512_sqr overflow bug on x86_64

> An integer overflow in OpenSSL's Montgomery squaring allows potential recovery of private keys from Diffie-Hellman operations, requiring an upgrade to secure versions.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/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:** 6 Dec 2019
- **Updated:** 8 Oct 2026
- **Also known as:** ALPINE-CVE-2019-1551, CLEANSTART-2026-JO98331, DEBIAN-CVE-2019-1551, DSA-4594-1, GHSA-fcc6-m5v9-xcgq, JLSEC-2026-216, MGASA-2020-0023, RHSA-2020:4514, SUSE-SU-2020:0002-1, SUSE-SU-2020:0028-1, SUSE-SU-2020:0064-1, SUSE-SU-2020:0069-1, SUSE-SU-2020:0474-1, UBUNTU-CVE-2019-1551, openSUSE-SU-2020:0062-1, openSUSE-SU-2024:10660-1

## What is CVE-2019-1551?

CVE-2019-1551 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 6 Dec 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

There is an overflow bug in the x64_64 Montgomery squaring procedure used in exponentiation with 512-bit moduli. No EC algorithms are affected. Analysis suggests that attacks against 2-prime RSA1024, 3-prime RSA1536, and DSA1024 as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH512 are considered just feasible. However, for an attack the target would have to re-use the DH512 private key, which is not recommended anyway. Also applications directly using the low level API BN_mod_exp may be affected if they use BN_FLG_CONSTTIME. Fixed in OpenSSL 1.1.1e (Affected 1.1.1-1.1.1d). Fixed in OpenSSL 1.0.2u (Affected 1.0.2-1.0.2t).

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2019-1551?

It affects 9 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `openssl` | Red Hat:enterprise_linux:8::baseos | All versions | 1:1.1.1g-11.el8 |
| `openssl-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 1:1.1.1g-11.el8 |
| `openssl-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 1:1.1.1g-11.el8 |
| `openssl-devel` | Red Hat:enterprise_linux:8::baseos | All versions | 1:1.1.1g-11.el8 |
| `openssl-libs` | Red Hat:enterprise_linux:8::baseos | All versions | 1:1.1.1g-11.el8 |
| `openssl-libs-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 1:1.1.1g-11.el8 |
| `openssl-perl` | Red Hat:enterprise_linux:8::baseos | All versions | 1:1.1.1g-11.el8 |
| `openssl` | SUSE:Enterprise Storage 5 | All versions | 1.0.2j-60.60.1 |
| `openssl-1_0_0` | SUSE:Enterprise Storage 6 | All versions | 1.0.2p-3.25.1 |
| `openssl` | SUSE:HPE Helion OpenStack 8 | All versions | 1.0.2j-60.60.1 |
| `openssl-1_0_0` | SUSE:Linux Enterprise Desktop 12 SP4 | All versions | 1.0.2p-3.14.1 |
| `openssl-1_1` | SUSE:Linux Enterprise Module for Basesystem 15 | All versions | 1.1.0i-4.27.1 |
| `openssl-1_1` | SUSE:Linux Enterprise Module for Basesystem 15 SP1 | All versions | 1.1.0i-14.6.1 |
| `openssl-1_0_0` | SUSE:Linux Enterprise Module for Legacy 15 | All versions | 1.0.2p-3.25.1 |
| `openssl-1_0_0` | SUSE:Linux Enterprise Module for Legacy 15 SP1 | All versions | 1.0.2p-3.25.1 |
| `openssl` | SUSE:Linux Enterprise Server 12 SP2-BCL | All versions | 1.0.2j-60.60.1 |
| `openssl` | SUSE:Linux Enterprise Server 12 SP2-LTSS | All versions | 1.0.2j-60.60.1 |
| `openssl` | SUSE:Linux Enterprise Server 12 SP3-BCL | All versions | 1.0.2j-60.60.1 |
| `openssl` | SUSE:Linux Enterprise Server 12 SP3-LTSS | All versions | 1.0.2j-60.60.1 |
| `openssl-1_0_0` | SUSE:Linux Enterprise Server 12 SP4 | All versions | 1.0.2p-3.14.1 |
| `openssl-1_0_0` | SUSE:Linux Enterprise Server 12 SP5 | All versions | 1.0.2p-3.14.1 |
| `openssl` | SUSE:Linux Enterprise Server for SAP Applications 12 SP2 | All versions | 1.0.2j-60.60.1 |
| `openssl` | SUSE:Linux Enterprise Server for SAP Applications 12 SP3 | All versions | 1.0.2j-60.60.1 |
| `openssl-1_0_0` | SUSE:Linux Enterprise Server for SAP Applications 12 SP4 | All versions | 1.0.2p-3.14.1 |
| `openssl-1_0_0` | SUSE:Linux Enterprise Server for SAP Applications 12 SP5 | All versions | 1.0.2p-3.14.1 |
| `openssl-1_0_0` | SUSE:Linux Enterprise Software Development Kit 12 SP4 | All versions | 1.0.2p-3.14.1 |
| `openssl-1_0_0` | SUSE:Linux Enterprise Software Development Kit 12 SP5 | All versions | 1.0.2p-3.14.1 |
| `openssl` | SUSE:OpenStack Cloud 7 | All versions | 1.0.2j-60.60.1 |
| `openssl` | SUSE:OpenStack Cloud 8 | All versions | 1.0.2j-60.60.1 |
| `openssl` | SUSE:OpenStack Cloud Crowbar 8 | All versions | 1.0.2j-60.60.1 |
| `openssl-1_1` | openSUSE:Leap 15.1 | All versions | 1.1.0i-lp151.8.6.1 |

Products: Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Openssl Openssl, Opensuse Leap, Oracle Enterprise Manager Ops Center, Oracle Mysql Enterprise Monitor, Oracle Peoplesoft Enterprise Peopletools, Tenable Log Correlation Engine.

## How do I fix CVE-2019-1551?

Upgrade to a fixed version.

## Is CVE-2019-1551 being exploited?

There is no known exploitation of CVE-2019-1551 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-2019-1551 and fix it if it is affected.

What it is: CVE-2019-1551 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 6 Dec 2019. 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-2019-1551 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-2019-1551/ (Markdown: https://insights.sbomify.com/CVE-2019-1551/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-1551
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1551
- OSV: https://osv.dev/vulnerability/CVE-2019-1551

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-1551/
Summaries are generated and may contain mistakes; the official description above is the record.