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CVE-2026-33191— free5GC UDM vulnerable to null byte injection in URL path parameters causing 500 Internal Server Error

Quick assessment

Affected
free5gc free5gc
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

free5GC是free5GC开源的一个第 5 代 (5G) 移动核心网络的开源项目。 Free5GC 1.4.2之前版本存在安全漏洞，该漏洞源于UDM的Nudm_SubscriberDataManagement API的supi路径参数存在空字节注入，可能导致拒绝服务攻击。

AI Predicted 7.5 Difficulty: Easy EPSS 0.58% · P46
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I. Basic Information for CVE-2026-33191

Vulnerability Information
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Vulnerability Title
free5GC UDM vulnerable to null byte injection in URL path parameters causing 500 Internal Server Error
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
空字节或NULL字符转义处理不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
free5GC 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
free5GC是free5GC开源的一个第 5 代 (5G) 移动核心网络的开源项目。 Free5GC 1.4.2之前版本存在安全漏洞，该漏洞源于UDM的Nudm_SubscriberDataManagement API的supi路径参数存在空字节注入，可能导致拒绝服务攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
free5gc free5gc < 1.4.2 -

II. Public POCs for CVE-2026-33191

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III. Intelligence Information for CVE-2026-33191

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Patches & Fixes for CVE-2026-33191 (1)

Vendor Advisories for CVE-2026-33191 (1)

Same Patch Batch · free5gc · 2026-03-20 · 7 CVEs total

CVE-2026-32937 free5GC CHF has Out-of-Bounds Slice Access that Leads to DoS
CVE-2026-33062 free5GC NRF Discovery EncodeGroupId Function Panics on Malformed group-id-list Parameter
CVE-2026-33063 free5GC AUSF UE Authentication Panic on Nil SuciSupiMap Interface Conversion
CVE-2026-33064 free5GC UDM DataChangeNotification Procedure Panic Due to Nil Pointer Dereference
CVE-2026-33065 free5GC UDM incorrectly returns 500 for empty supi path parameter in DELETE sdm-subscripti
CVE-2026-33192 free5GC UDM incorrectly returns 500 for empty supi path parameter in PATCH sdm-subscriptio

IV. Related Vulnerabilities

Same product: free5gc
Same vendor: free5gc
Same weakness: CWE-158

V. Comments for CVE-2026-33191

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