Cyber Resilience

CVE-2026-41135

DoS in Free5Gc ≤ 4.2.1

Public PoCDoS
Published
22 April 2026
Modified
23 April 2026
Patch / advisory
CVSS Score v3.1 7.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.0052 41th percentile
Risk Priority 58 floored blend · peak EPSS

Summary

CVE-2026-41135 is a high-severity Uncontrolled Resource Consumption (CWE-400) vulnerability in Free5Gc Free5Gc. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique OS Exhaustion Flood (T1499.001); ranked at the 41th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SC-5 (Denial-of-service Protection) and SC-6 (Resource Availability) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-41135 is a memory leak vulnerability in the Policy Control Function (PCF) component of free5GC, an open-source implementation of a 5G mobile core network. The issue affects versions prior to 1.4.3 and stems from a `router.Use()` call within an HTTP handler that registers a new CORS middleware instance on every incoming request to the PCF's Service-Based Interface (SBI). This permanently extends the Gin router's handler chain, resulting in progressive memory exhaustion. The vulnerability is rated 7.5 on the CVSS v3.1 scale (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) and is associated with CWE-400 (Uncontrolled Resource Consumption).

Any unauthenticated attacker with network access to the PCF SBI interface can exploit this vulnerability by sending repeated HTTP requests to the Operations, Administration, and Maintenance (OAM) endpoint. This triggers uncontrolled memory growth, eventually causing Denial of Service (DoS) on the PCF. As a result, all User Equipments (UEs) are prevented from obtaining Access and Mobility Management (AM) or Session Management (SM) policies, blocking 5G session establishment.

The free5GC security advisory (GHSA-98cp-84m9-q3qp) details the issue and confirms that version 1.4.3 includes a patch addressing the root cause. The specific fix is implemented in commit 599803b1b2eb4611e26d5216481ee142bce71a16 in the free5gc/pcf repository, which resolves the improper middleware registration. Security practitioners should upgrade to free5GC 1.4.3 or later to mitigate the vulnerability.

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1499.001 OS Exhaustion Flood Impact
Adversaries may launch a denial of service (DoS) attack targeting an endpoint's operating system (OS).
T1498 Network Denial of Service Impact
Adversaries may perform Network Denial of Service (DoS) attacks to degrade or block the availability of targeted resources to users.
T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
T1499.002 Service Exhaustion Flood Impact
Adversaries may target the different network services provided by systems to conduct a denial of service (DoS).
T1499.003 Application Exhaustion Flood Impact
Adversaries may target resource intensive features of applications to cause a denial of service (DoS), denying availability to those applications.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-60638Same product: Free5Gc Free5Gc
CVE-2023-47025Same product: Free5Gc Free5Gc
CVE-2026-30653Same product: Free5Gc Free5Gc
CVE-2026-1974Same product: Free5Gc Free5Gc
CVE-2026-2525Same product: Free5Gc Free5Gc
CVE-2026-1683Same product: Free5Gc Free5Gc
CVE-2026-1684Same product: Free5Gc Free5Gc
CVE-2026-1975Same product: Free5Gc Free5Gc
CVE-2026-1739Same product: Free5Gc Pcf
CVE-2026-1976Same product: Free5Gc Free5Gc

Affected Assets

free5gc
free5gc
≤ 4.2.1
free5gc
pcf
≤ 1.4.3

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SC-5 directly limits the effects of resource-exhaustion events that constitute uncontrolled consumption.

SC-6 enforces explicit allocation limits on resources, structurally preventing the weakness from occurring.

Process isolation confines resource consumption to separate domains, reducing blast radius without stopping the root flaw.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.IR-04 mostly match
prevents

Explicitly requires monitoring and maintaining resource capacity, directly addressing uncontrolled consumption to preserve availability.

DE.CM-09 partial match
prevents

Continuous monitoring of computing resources can detect resource exhaustion but does not itself enforce allocation limits.

PR.IR-03 partial match
prevents

Resilience mechanisms such as avoiding single points of failure indirectly reduce impact of resource exhaustion.

PR.PS-01 partial match
prevents

Hardened configuration baselines can include resource quotas and limits that constrain consumption.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

finds

Resource-utilization monitoring and alerting on bottlenecks or overloads limits the impact of denial-of-service or resource-exhaustion attacks.

prevents

By continuously monitoring utilization, stress-testing peak loads, and maintaining documented plans to scale or throttle resources, the control directly limits an attacker’s ability to drive a system into uncontrolled resource exhaustion.

finds

Pre-agreed severity-based prioritization and resource allocation during incident triage reduce the likelihood that an attacker-induced resource exhaustion will overwhelm the organization before corrective action is taken.

mitigates

Business-continuity plans that include resource-management controls reduce the likelihood that an attacker can trigger uncontrolled resource consumption by forcing the system into a degraded or fallback state.

mitigates

Defining RTOs and capacity requirements for ICT services during business-impact analysis forces organizations to provision sufficient resources and throttling mechanisms, reducing the likelihood that an attacker can induce denial-of-service through uncontrolled resource consumption.

finds

Early notification of anomalous resource consumption or system malfunctions enables throttling or isolation before availability is lost.

References