CVE-2026-7781Public exploitNetwork attack vector

UDM crash via missing registration-state assertion

Published May 4, 2026 · Updated May 4, 2026

Denial of service in Open5GS 2.7.0 through 2.7.7 allows remote authenticated users to crash the UDM via a crafted registration update. In udm_nudm_uecm_handle_amf_registration_update(), purgeFlag processing asserts that a fresh UE context already has AMF registration state, while unsupported child routes reach the same handler. SBI network access and low privileges are required; triggering the assertion aborts the UDM process and interrupts registration services.

CVSS severity4.3
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Open5GS 2.7.0 through 2.7.7 allows remote authenticated users to crash the UDM via a crafted registration update. In udm_nudm_uecm_handle_amf_registration_update(), purgeFlag processing asserts that a fresh UE context already has AMF registration state, while unsupported child routes reach the same handler. SBI network access and low privileges are required; triggering the assertion aborts the UDM process and interrupts registration services.

The record

CVE
CVE-2026-7781
Published
May 4, 2026
Updated
May 4, 2026
Vendor
Open5GS
Product
Open5GS
Classifications
CWE-404, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 4, 2026CVE publishedPublication date reported by the CVE source.
  2. May 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.7.0
  2. Affected versionversion=2.7.1
  3. Affected versionversion=2.7.2
  4. Affected versionversion=2.7.3
  5. Affected versionversion=2.7.4
  6. Affected versionversion=2.7.5
  7. Affected versionversion=2.7.6
  8. Affected versionversion=2.7.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Open5GS · Open5GSversion=2.7.0; version=2.7.1; version=2.7.2; version=2.7.3; version=2.7.4; version=2.7.5; version=2.7.6; version=2.7.7

Published CVSS scores

4.3VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
2.1VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
4.0VulDBAV:N/AC:L/Au:S/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-404Improper Resource Shutdown or Release
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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