Improper input validation in Free5gc Udm
CVE-2026-27642
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.
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.007 (49.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 49th percentile — 49.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.007 · change: +0.001
Affected products
- Free5gc Udm — versions <= 1.4.1
Weakness classification (CWE)
References
- github.com/free5gc/free5gc/security/advisories/GHSA-h4wg-rp7m-8xx4 (Vendor Advisory)
- github.com/free5gc/free5gc/issues/749 (Exploit, Issue Tracking, Vendor Advisory)
- github.com/free5gc/udm/pull/75 (Patch, Issue Tracking)
- github.com/free5gc/udm/commit/a7af2321ddea6368c43835f90f6d1b9d67dd2ea1 (Patch)
Frequently asked questions
- What is CVE-2026-27642?
- CVE-2026-27642 is a high-severity vulnerability in Free5gc Udm, classified under Improper Input Validation. CVSS score: 7.5/10. Published 2026-02-24.
- How severe is CVE-2026-27642?
- High severity. CVSS v3 base score is 7.5 out of 10.