CVE-2021-34598Network attack vector

System restart via unreleased syslog-ng data structures

Published Nov 10, 2021 · Updated Sep 16, 2024

Resource exhaustion in Phoenix Contact FL MGUARD 1102 and 1105 1.4.0 through 1.5.0 allows remote attackers to trigger a system restart. With remote logging active, syslog-ng fails to release data structures as attacker-generated events accumulate, exhausting appliance memory. No authentication or user interaction is required, but remote logging must be enabled; the documented consequence is a restart and resulting service interruption.

CVSS severity7.5
High
EPSS probability0.93%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Resource exhaustion in Phoenix Contact FL MGUARD 1102 and 1105 1.4.0 through 1.5.0 allows remote attackers to trigger a system restart. With remote logging active, syslog-ng fails to release data structures as attacker-generated events accumulate, exhausting appliance memory. No authentication or user interaction is required, but remote logging must be enabled; the documented consequence is a restart and resulting service interruption.

The record

CVE
CVE-2021-34598
Published
Nov 10, 2021
Updated
Sep 16, 2024
Vendor
Phoenix Contact
Product
FL MGUARD
Classifications
CWE-401, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 10, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=1.4.0 <FL MGUARD 1102 (No. 1153079)*
  2. Affected versionversion=1.4.0 <FL MGUARD 1105 (No. 1153078)*

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Phoenix Contact · FL MGUARDversion=1.4.0 <FL MGUARD 1102 (No. 1153079)*; version=1.4.0 <FL MGUARD 1105 (No. 1153078)*

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
7.5CERT VDECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
T1499.002Service Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo