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Path TraversalWeakness · CWE-22

CVE-2021-31156

HIGH · 7.5 CVSS v3.1 Published 2024-03-28
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
Allied Telesis AT-S115 1.2.0 devices before 1.00.024 with Boot Loader 1.00.006 allow Directory Traversal to achieve partial access to data.

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 · moderate confidence

Directory traversal vulnerability in Allied Telesis AT-S115 wireless access points allows remote attackers to escape the web root directory using '../' path sequences, enabling unauthorized access to files outside the intended document root. The vulnerability affects firmware versions before 1.00.024 with Boot Loader 1.00.006, resulting in partial data exposure.

MitigationUpgrade firmware to version 1.00.024 or later which contains the patch for this directory traversal vulnerability. If immediate patching is not possible, restrict network access to the device management interface.

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
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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 checks

Work through these to decide whether this CVE applies to you.

  1. Confirm device is an AT-S115 wireless access point
    Access the device's web management interface or check the device label/model information to verify the exact model number is AT-S115
    Affected if The device model is not AT-S115 (different models are not affected by this specific CVE)
  2. Check firmware version
    Log into the web interface and navigate to the Status or System Information page to view the installed firmware version, or use SNMP/CLI to query the firmware version
    Affected if Firmware version is below 1.00.024 (versions 1.00.000 through 1.00.023 are affected)
  3. Check Boot Loader version
    Access the device status page or boot loader information through the web UI or console to identify the Boot Loader version
    Affected if Boot Loader version is 1.00.006 (this is the vulnerable Boot Loader version mentioned in the CVE)
  4. Verify web management interface is enabled
    Check the device configuration to confirm the web-based management interface is currently enabled and accessible over the network
    Affected if The web interface is enabled and reachable - the directory traversal vulnerability exists in the embedded web server component

Your device is affected if it is an AT-S115 with firmware versions prior to 1.00.024 running Boot Loader 1.00.006 and the web management interface is enabled.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade firmware to version 1.00.024 or later which contains the patch for this directory traversal vulnerability. If immediate patching is not possible, restrict network access to the device management interface.

Recommended fix Low confidence

Firmware version 1.00.024 or later

  1. Identify the current firmware version of the AT-S115 device through the web management interface or CLI
  2. Download firmware version 1.00.024 or later from the Allied Telesis support website
  3. Access the device management interface and navigate to the firmware upgrade section
  4. Upload and apply the new firmware file following the manufacturer's upgrade procedure
  5. After upgrade, verify the device is running firmware version 1.00.024 or later
  6. Verify the path traversal vulnerability is resolved by testing access restrictions

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-31156 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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