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Vulnerability record · CVE-2026-27642 · published 24 February 2026

CVE-2026-27642: Free5gc udm improper input validation vulnerability

Free5gc · Udm

free5gc UDM provides Unified Data Management (UDM) for free5GC, an open-source project for 5th generation (5G) mobile core networks. In versions up to and including 1.4.1, remote attackers can inject control characters (e.g., %00) into the supi parameter, triggering internal URL parsing errors (net/url: invalid control character). This exposes system-level error details and can be used for service fingerprinting. All deployments of free5GC using the UDM Nudm_UEAU service may be affected. free5gc/udm pull request 75 contains a fix for the issue. No direct workaround is available at the application level. Applying the official patch is recommended.

6.6 CVSS 4.0 Medium EPSS 0.65% · top 50.9% CWE-20 · Improper input validation
6.6CVSS 4.0 base score
0.65%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 1 tagged exploit
17 Jun 2026Last modified by NVD

Description

free5gc UDM provides Unified Data Management (UDM) for free5GC, an open-source project for 5th generation (5G) mobile core networks. In versions up to and including 1.4.1, remote attackers can inject control characters (e.g., %00) into the supi parameter, triggering internal URL parsing errors (net/url: invalid control character). This exposes system-level error details and can be used for service fingerprinting. All deployments of free5GC using the UDM Nudm_UEAU service may be affected. free5gc/udm pull request 75 contains a fix for the issue. No direct workaround is available at the application level. Applying the official patch is recommended.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/free5gc/free5gc/issues/749 ExploitIssue TrackingVendor Advisory
https://github.com/free5gc/free5gc/security/advisories/GHSA-h4wg-rp7m-8xx4 Vendor Advisory
https://github.com/free5gc/udm/commit/a7af2321ddea6368c43835f90f6d1b9d67dd2ea1 Patch
https://github.com/free5gc/udm/pull/75 Issue TrackingPatch

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-27642), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.