# CVE-2026-32686: Unbounded exponent in decimal enables unauthenticated DoS

> Attackers can crash the BEAM VM by sending decimal inputs with huge exponents, causing memory exhaustion in applications using the decimal library.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 May 2026
- **Updated:** 8 Sep 2026
- **Also known as:** EEF-CVE-2026-32686, GHSA-rhv4-8758-jx7v

## What is CVE-2026-32686?

CVE-2026-32686 is a medium-severity denial of service vulnerability in ericmj decimal, published on 7 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Uncontrolled Resource Consumption vulnerability in ericmj decimal allows unauthenticated remote Denial of Service.

The decimal library does not bound the exponent on parsed input. Storing a decimal with a very large exponent (e.g. Decimal.new("1e1000000000")) is accepted without error. Subsequent calls to arithmetic functions (Decimal.add/2, Decimal.sub/2, Decimal.div/2M), Decimal.to_string/2M with :normalM or :xsdM format, Decimal.to_integer/1M, Decimal.round/3M, or Decimal.compare/3M with a threshold allocate memory proportional to the exponent value, which can exhaust available memory and crash the BEAM VM.

Any application that accepts user-supplied decimal input and subsequently performs arithmetic, rounding, conversion to integer, or string formatting on it is exposed. A single malicious request is sufficient to cause an out-of-memory crash.

This issue affects decimal: from 0.1.0 before 3.0.0.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-32686?

3 open source packages ship an affected version, including decimal.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `decimal` | Hex | From 0.1.0 | 3.0.0 |
| `decimal` | Hex | From 0.1.0 | 3.0.0 |
| `decimal` | Hex | From 0.1.0 | 3.0.0 |

## How do I fix CVE-2026-32686?

Upgrade decimal to 3.0.0 or later.

## Is CVE-2026-32686 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-32686 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-32686 and fix it if it is affected.

What it is: CVE-2026-32686 is a medium-severity denial of service vulnerability in ericmj decimal, published on 7 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-32686 exists.

Affected packages and fixed versions:
- decimal (Hex): affected from 0.1.0; fixed in 3.0.0
- decimal (Hex): affected from 0.1.0; fixed in 3.0.0
- decimal (Hex): affected from 0.1.0; fixed in 3.0.0

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-2026-32686/ (Markdown: https://insights.sbomify.com/CVE-2026-32686/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-32686
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-32686
- OSV: https://osv.dev/vulnerability/CVE-2026-32686

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-32686/
Summaries are generated and may contain mistakes; the official description above is the record.