CVE-2019-11823Public exploitNetwork attack vector

Service crashes via unchecked DHCP hostname newline

Published May 4, 2020 · Updated Sep 16, 2024

CRLF injection in Network Center in Synology Router Manager before 1.2.3-8017-2 allows remote attackers to crash monitoring services. The DHCP monitor writes newline-bearing hostnames to /var/run/device.dhcp, then reads a missing fourth tab-delimited field and passes its out-of-bounds pointer to strtol. Remote attackers on a DHCP-reachable network require no account and can repeatedly stop synomonitordhcpd and synodeviced until a manual router reboot is required.

CVSS severity8.6
High
EPSS probability2.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CRLF injection in Network Center in Synology Router Manager before 1.2.3-8017-2 allows remote attackers to crash monitoring services. The DHCP monitor writes newline-bearing hostnames to /var/run/device.dhcp, then reads a missing fourth tab-delimited field and passes its out-of-bounds pointer to strtol. Remote attackers on a DHCP-reachable network require no account and can repeatedly stop synomonitordhcpd and synodeviced until a manual router reboot is required.

The record

CVE
CVE-2019-11823
Published
May 4, 2020
Updated
Sep 16, 2024
Vendor
Synology
Product
Synology Router Manager (SRM)
Classifications
CWE-125, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 4, 2020CVE 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

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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=unspecified <1.2.3-8017-2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Synology · Synology Router Manager (SRM)version=unspecified <1.2.3-8017-2

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
8.6Synology Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499.004Endpoint Denial of Service Application 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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