CVE-2026-27642: free5GC has Improper Input Validation in UDM UEAU Service
Vulnerability summary
CVE-2026-27642 is a high (CVSS 7.5) Improper Input Validation vulnerability in free5gc udm. EPSS estimates a 0.73% chance of exploitation in the next 30 days, higher than 53.6% of scored vulnerabilities. 1 public exploit is recorded.
Timeline
- 24-02-2026PublishedVulnerability first disclosed.
- 26-02-2026Last modifiedVulnerability information updated.
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 metrics
3 scores · 2 sources · 2 versions- NVDNIST6.6MediumCVSS: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:X/V:X/RE:X/U:X
EPSS trend
Probability
0.73%
Chance of exploitation in the next 30 days
Percentile
54%
Versus all other CVEs
30-day change
Increase +0.22 pp
From 0.51% on 22-09-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
1 foundFree5Gc
Maturity: poc
Weaknesses
CWE · root causeAffected systems
Free5gc1 product
- udm≤ 1.4.1
1 vendor · 1 product
References
4 links- github.com/free5gc/free5gc/security/advisories/GHSA-h4wg-rp7m-8xx4X Refsource CONFIRMVendor Advisory