CVE-2021-3254Public exploitNetwork attack vector

Persistent service outage via TCP SYN scan

Published May 11, 2022 · Updated Aug 3, 2024

Denial of service in ASUS DSL-N14U-B1 firmware 1.1.2.3_805 allows remote attackers to crash three network services via a TCP SYN scan. The Printer Job Language probe makes the jetdirect, LPD, and sos processes disappear, but the underlying packet-handling defect is undisclosed. No authentication or user interaction is required, and the services remain unavailable until the router is physically rebooted.

CVSS severity7.5
High
EPSS probability1.77%
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 ASUS DSL-N14U-B1 firmware 1.1.2.3_805 allows remote attackers to crash three network services via a TCP SYN scan. The Printer Job Language probe makes the jetdirect, LPD, and sos processes disappear, but the underlying packet-handling defect is undisclosed. No authentication or user interaction is required, and the services remain unavailable until the router is physically rebooted.

The record

CVE
CVE-2021-3254
Published
May 11, 2022
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 11, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.8NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:C

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

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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