CVE-2026-42459: free5GC is an open-source implementation of the 5G core network

Q: How do I fix CVE-2026-42459?

free5gc: upgrade to 4.2.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-42459 being exploited?

CVE-2026-42459 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-42459 affect?

CVE-2026-42459 affects free5gc. Severity is high (CVSS 7.5). free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, the free5GC UDM component fails to validate the supi path parameter in six GET handlers of the nudm-sdm (Subscriber Data Management) service. An unauthenticate

Q: How urgent is CVE-2026-42459?

Priority 43/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 7.5REMOTEUPGRADE

CVE-2026-42459 is a high-severity flaw (CVSS 7.5) affecting free5gc. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, the free5GC UDM component fails to validate the supi path parameter in six GET handlers of the nudm-sdm (Subscriber Data Management) service. An unauthenticated attacker can inject control characters into the SUPI parameter, causing UDM to forward a malformed request to UDR and return a 500 Internal Server Error response that exposes internal infrastructure details.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 75%)
CISA exploited list	No
Weakness	CWE-20, CWE-209
Published	2026-05-27
Last modified	2026-10-14

Publisher (CNA): GitHub, Inc. · Vendor: free5gc

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-27 17:16 UTCPublished CVE record published
2026-10-14 20:10 UTCUpdated Record last modified

free5gc free5gc UPGRADE

Affected: < 4.2.2

Fixed in: 4.2.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy free5gc || rpm -q free5gc || free5gc --version

2. UPGRADE to 4.2.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade free5gc

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade free5gc

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-42459?

free5gc: upgrade to 4.2.2. Exact commands for each OS are on this page.

Is CVE-2026-42459 being exploited?

CVE-2026-42459 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-42459 affect?

CVE-2026-42459 affects free5gc. Severity is high (CVSS 7.5). free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, the free5GC UDM component fails to validate the supi path parameter in six GET handlers of the nudm-sdm (Subscriber Data Management) service. An unauthenticate

How urgent is CVE-2026-42459?

Priority 43/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-40343 MEDIUM 5.8 UPGRADE UPGRADE free5GC UDR is the user data repository (UDR) for free5GC, an an open-source project for 5th generation (5G) m
CVE-2026-41135 HIGH 7.5 UPGRADE UPGRADE free5GC UDR is the Policy Control Function (PCF) for free5GC, an an open-source project for 5th generation (5G
CVE-2026-41136 MEDIUM 5.3 UPGRADE UPGRADE free5GC AMF provides Access & Mobility Management Function (AMF) for free5GC, an an open-source project for 5t
CVE-2026-44329 CRITICAL 10.0 UPGRADE free5GC is an open-source implementation of the 5G core network
CVE-2026-44327 CRITICAL 10.0 UPGRADE free5GC is an open-source implementation of the 5G core network

References

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