CyberSecBulletin
CVE-2026-23767NVD status: Analyzed

ESC/POS: Missing Authentication for Critical Functionality

Published Updated By the CyberSecBulletin desk

CVE-2026-23767 is a critical-severity missing authentication for critical functionality vulnerability in ESC/POS from Seiko Epson, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected ESC/POS versions: All products implementing ESC/POS. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.5% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Check which version of ESC/POS you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on epson.jp for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Seiko EpsonESC/POSAll products implementing ESC/POSNot stated
EpsonSb-h50 FirmwareNot specified in the recordNot stated
EpsonTm-h6000v FirmwareNot specified in the recordNot stated
EpsonTm-l100 FirmwareNot specified in the recordNot stated
EpsonTm-m10 FirmwareNot specified in the recordNot stated
EpsonTm-m30 FirmwareNot specified in the recordNot stated
EpsonTm-m30ii FirmwareNot specified in the recordNot stated
EpsonTm-m30ii-h FirmwareNot specified in the recordNot stated
EpsonTm-m30ii-s FirmwareNot specified in the recordNot stated
EpsonTm-m30ii-sl FirmwareNot specified in the recordNot stated
EpsonTm-m30iii FirmwareNot specified in the recordNot stated
EpsonTm-m30iii-h FirmwareNot specified in the recordNot stated
EpsonTm-m55 FirmwareNot specified in the recordNot stated
EpsonTm-p20ii FirmwareNot specified in the recordNot stated
EpsonTm-p80ii FirmwareNot specified in the recordNot stated
EpsonTm-p20 FirmwareNot specified in the recordNot stated
EpsonTm-p60ii FirmwareNot specified in the recordNot stated
EpsonTm-p80 FirmwareNot specified in the recordNot stated
EpsonTm-t20ii FirmwareNot specified in the recordNot stated
EpsonTm-t20iii FirmwareNot specified in the recordNot stated
EpsonTm-t88vi FirmwareNot specified in the recordNot stated
EpsonTm-t88vi-ihub FirmwareNot specified in the recordNot stated
EpsonTm-t88vii FirmwareNot specified in the recordNot stated
EpsonUb-r04 FirmwareNot specified in the recordNot stated
EpsonUb-e04 FirmwareNot specified in the recordNot stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CISA (ADP).

Official description

ESC/POS, a printer control language designed by Seiko Epson Corporation, lacks mechanisms for user authentication and command authorization, does not provide controls to restrict sources or destinations of network communication, and transmits commands without encryption or integrity protection.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Missing Authentication for Critical Functionality

The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

How developers prevent this class of flaw

  • For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator.
  • When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data.

More Missing Authentication for Critical Functionality vulnerabilities (CWE-306)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Recent Missing Authentication for Critical Functionality vulnerabilities

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