Free5GC up to 1.4.1 URL Parser Nudm_SubscriberDataManagement null byte or nul character

CVSS Meta Temp Score
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CTI Interest Score
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6.3$0-$5k0.00

Summaryinfo

A vulnerability labeled as problematic has been found in Free5GC up to 1.4.1. Affected by this issue is the function Nudm_SubscriberDataManagement of the component URL Parser. Executing a manipulation can lead to improper neutralization of null byte or nul character. This vulnerability is tracked as CVE-2026-33191. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability has been found in Free5GC up to 1.4.1 and classified as problematic. This vulnerability affects the function Nudm_SubscriberDataManagement of the component URL Parser. The manipulation with an unknown input leads to a improper neutralization of null byte or nul character vulnerability. The CWE definition for the vulnerability is CWE-158. The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes NUL characters or null bytes when they are sent to a downstream component. As an impact it is known to affect availability. CVE summarizes:

Free5GC is an open-source Linux Foundation project for 5th generation (5G) mobile core networks. Versions prior to 1.4.2 are vulnerable to null byte injection in URL path parameters. A remote attacker can inject null bytes (URL-encoded as %00) into the supi path parameter of the UDM's Nudm_SubscriberDataManagement API. This causes URL parsing failure in Go's net/url package with the error "invalid control character in URL", resulting in a 500 Internal Server Error. This null byte injection vulnerability can be exploited for denial of service attacks. When the supi parameter contains null characters, the UDM attempts to construct a URL for UDR that includes these control characters. Go's URL parser rejects them, causing the request to fail with 500 instead of properly validating input and returning 400 Bad Request. This issue has been fixed in version 1.4.2.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-33191 since 03/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 303463 (Linux Distros Unpatched Vulnerability : CVE-2026-33191), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.4.2 eliminates this vulnerability. Applying the patch 88de9fa74a1b3f3522e53b4cfa2d184712ffa4ee is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (303463). Once again VulDB remains the best source for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 8.6
NVD Vector: 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Improper neutralization of null byte or nul character
CWE: CWE-158 / CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 303463
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-33191

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Free5GC 1.4.2
Patch: 88de9fa74a1b3f3522e53b4cfa2d184712ffa4ee

Timelineinfo

03/17/2026 CVE reserved
03/20/2026 +3 days Advisory disclosed
03/20/2026 +0 days VulDB entry created
03/26/2026 +6 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-p9hg-pq3q-v9gv
Status: Confirmed

CVE: CVE-2026-33191 (🔒)
GCVE (CVE): GCVE-0-2026-33191
GCVE (VulDB): GCVE-100-352012

Entryinfo

Created: 03/20/2026 09:28
Updated: 03/26/2026 12:45
Changes: 03/20/2026 09:28 (69), 03/25/2026 03:44 (2), 03/26/2026 12:45 (12)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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