CVE-2026-33191

HIGH EPSS 27.3%
Published Mar 20, 20263mo ago · Modified Mar 23, 20263mo ago
8.7 CVSS 4.0
High
Find Similar
Published Mar 20, 2026 3mo ago
Last Modified Mar 23, 2026 3mo ago

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.

CVSS Details

Base Score
8.7
Exploitability
—
Impact
—
Vector string
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
27.3% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 2

CWE-158
CWE-248

Affected Products 1

VendorProductVersionRange
free5gcudm* <1.4.2

References 2

  • github.com https://github.com/free5gc/free5gc/security/advisories/GHSA-p9hg-pq3q-v9gv
    PatchVendor Advisory
  • github.com https://github.com/free5gc/udm/commit/88de9fa74a1b3f3522e53b4cfa2d184712ffa4ee
    Patch

Remediation

  • github.com https://github.com/free5gc/free5gc/security/advisories/GHSA-p9hg-pq3q-v9gv
    PatchVendor Advisory
  • github.com https://github.com/free5gc/udm/commit/88de9fa74a1b3f3522e53b4cfa2d184712ffa4ee
    Patch