CVE-2023-40708Network attack vector

Unauthenticated file access via default-open FTP

Published Aug 24, 2023 · Updated Oct 2, 2024

Improper access control in Opto 22 SNAP PAC S1 firmware R10.3b allows remote attackers to read device files through FTP. The firmware starts its FTP server on TCP port 21 by default, exposing some controller files to unauthenticated network clients. No privileges or user interaction are required; a network path to the controller is enough to read the exposed files.

CVSS severity5.8
Medium
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Opto 22 SNAP PAC S1 firmware R10.3b allows remote attackers to read device files through FTP. The firmware starts its FTP server on TCP port 21 by default, exposing some controller files to unauthenticated network clients. No privileges or user interaction are required; a network path to the controller is enough to read the exposed files.

The record

CVE
CVE-2023-40708
Published
Aug 24, 2023
Updated
Oct 2, 2024
Vendor
Opto 22
Product
SNAP PAC S1
Classifications
CWE-1188, T0822
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 24, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 2, 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=r10.3b
  2. Affected versionversion=R10.3b

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Opto 22 · SNAP PAC S1version=r10.3b; version=R10.3b

Published CVSS scores

5.8DragosCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-1188Initialization of a Resource with an Insecure Default
T0822External Remote Services

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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