CVE-2026-23759
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedPerle IOLAN STS/SCS terminal server models with firmware versions prior to 6.0 allow authenticated OS command injection via the restricted shell accessed over Telnet or SSH. The shell 'ps' command does not perform proper argument sanitization and passes user-supplied parameters into an 'sh -c' invocation running as root. An authenticated attacker who can log in to the device can inject shell metacharacters after the 'ps' subcommand to execute arbitrary OS commands with root privileges, leading to full compromise of the underlying operating system.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidencePerle IOLAN STS/SCS terminal servers with firmware prior to 6.0 contain an authenticated OS command injection vulnerability in the restricted shell. The 'ps' command fails to sanitize user-supplied arguments, passing them directly to an 'sh -c' invocation running as root, allowing authenticated attackers to execute arbitrary commands with root privileges.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify the firmware versionAccess the Perle IOLAN STS/SCS web interface or CLI and navigate to System Information or Firmware Version settings to retrieve the current firmware versionAffected if The firmware version is shown as anything earlier than 6.0 (e.g., 5.x, 4.x, etc.)
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Confirm SSH or Telnet access is enabledCheck the device network settings via the web interface or CLI to verify that SSH or Telnet access is enabled for remote administrationAffected if SSH or Telnet access is enabled, providing a pathway for authenticated attackers to reach the restricted shell
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Verify the restricted shell is accessibleLog into the device via SSH or Telnet using valid administrative credentials and attempt to access the restricted shell environment. The vulnerability exists in the 'ps' command within this shellAffected if Authenticated access to the restricted shell is possible and the 'ps' command accepts unsanitized arguments
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Test for command injection in the ps commandWhile authenticated in the restricted shell, execute the 'ps' command with a test argument such as '; echo test' to observe if command injection occurs (e.g., ps ; echo test)Affected if The ps command executes the injected argument, confirming the lack of input sanitization
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Check if device is exposed to untrusted networksReview the network configuration to determine if the management interface (SSH/Telnet) is accessible from untrusted or public networks rather than isolated management networksAffected if The management interface is reachable from untrusted networks, increasing the likelihood of exploitation by external authenticated attackers
A defender is affected if their Perle IOLAN STS/SCS firmware is version 5.x or earlier, SSH or Telnet access is enabled, and the restricted shell with the vulnerable ps command is accessible to authenticated users.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade Perle IOLAN STS/SCS firmware to version 6.0 or later to address the command injection vulnerability. If immediate patching is not feasible, restrict Telnet/SSH access to trusted management networks and enforce strong authentication credentials.
Firmware version 6.0 or later
- Access the Perle IOLAN STS/SCS device management interface via web browser or console
- Navigate to the firmware upgrade section (typically under System > Firmware or Administration > Firmware Update)
- Identify the current firmware version to confirm it is prior to 6.0
- Download the firmware version 6.0 or later from the official Perle support website (www.perle.com)
- Upload the firmware file to the device and initiate the upgrade process
- Allow the device to complete the upgrade and reboot automatically
- After reboot, verify the new firmware version is 6.0 or later
- Reapply device configuration if not automatically preserved
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-23759 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-23759 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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