Home/CVE/free5GC UDR is the user data repository (UDR) for free5GC, an an open-source project for 5th generation (5G) mobile core
CVE

CVE-2026-40343

free5GC UDR is the user data repository (UDR) for free5GC, an an open-source project for 5th generation (5G) mobile core

free5GC UDR is the user data repository (UDR) for free5GC, an open-source project for 5th generation (5G) mobile core networks. In versions up to and including 1.4.2, a fail-open request handling flaw in the UDR service causes the /nudr-dr/v2/policy-data/subs-to-notify POST handler to continue processing requests even after request body retrieval or deserialization errors. This may allow unintended creation of Policy Data notification subscriptions with invalid, empty, or partially processed input, depending on downstream processor behavior.

As of time of publication, a patched version is not available.

MEDIUM · CVSS 5.8 EPSS 0.0006
Schedule remediation
  • SSVC automatable: yes - attacks can be scripted at scale
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-754Improper Check for Unusual or Exceptional Conditions
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Affected Products & Versions

2
free5gc<= 4.2.1
free5gc udr<= 1.4.2
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Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Go github.com/free5gc/udr MODERATE
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Detection Rules (IDS/IPS)

3
et-openET EXPLOIT free5GC UDR Fail-Open Abuse - Empty Body (CVE-2026-40343)web-application-attack
et-openET EXPLOIT free5GC UDR Fail-Open Abuse - Truncated JSON (CVE-2026-40343)web-application-attack
et-openET EXPLOIT free5GC UDR Fail-Open Abuse - Invalid JSON (CVE-2026-40343)web-application-attack
Open rulesets (ET Open, Snort Community, abuse.ch) link to source. Commercial rulesets are reference-only.
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Scoring & Timeline

5.8
MEDIUM · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD22 Apr 2026 · 12:16 AM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/free5gc/free5gc/security/advisories/GHSA-jwch-w7wh-gqjmMitigationPatchVendor Advisory
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