dbcve.org
Path TraversalWeakness · CWE-22

CVE-2026-43982

HIGH · 8.7 CVSS v4.0 Published 2026-05-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
96/100
Remediation priority · Urgent
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
Algernon is a small self-contained pure-Go web server. Prior to 1.17.6, uploadedFileSaveIn() in lua/upload/upload.go uses filepath.Join() with the caller-supplied directory but performs no boundary check after joining. A directory of ../../../tmp resolves cleanly to /tmp, outside the web root. This vulnerability is fixed in 1.17.6.

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 confidence

Path traversal vulnerability in Algernon's uploadedFileSaveIn() function allows attackers to escape the intended upload directory by supplying path traversal sequences like ../../../tmp in the user-controlled directory parameter, enabling file writes to arbitrary locations outside the web root.

MitigationUpgrade to version 1.17.6 or later, which implements proper path boundary validation after filepath.Join() to ensure uploads remain within the intended directory.

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
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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. Identify Algernon installation and version
    Run 'algernon --version' or check the binary metadata. If running as a service, check the process list for algernon executables.
    Affected if The installed version is below 1.17.6 (the fixed version)
  2. Locate the upload handler configuration
    Search configuration files (algernon.conf, any .lua scripts in the web root, or embedded Lua code) for calls to 'uploadedFileSaveIn' or file upload handling functions.
    Affected if The uploadedFileSaveIn() function is configured and in use
  3. Determine the intended upload directory
    Examine the upload configuration to identify the base directory specified for file uploads (the argument passed to uploadedFileSaveIn).
    Affected if A base upload directory is configured that can be escaped via path traversal (e.g., writable directories like /tmp or web root directories)
  4. Check for path boundary validation
    Inspect the Algernon binary or source code (lua/upload/upload.go) for path validation logic after filepath.Join() calls. Look for functions that resolve paths and compare them against the base directory using functions like filepath.Clean, filepath.EvalSymlinks, or explicit prefix checks.
    Affected if No boundary validation code exists after filepath.Join() in the upload handling path, making traversal possible

A defender is affected if they run Algernon versions below 1.17.6, have the uploadedFileSaveIn() upload feature enabled, and do not have compensating path boundary validation in place.

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 to version 1.17.6 or later, which implements proper path boundary validation after filepath.Join() to ensure uploads remain within the intended directory.

Recommended fix High confidence

version 1.17.6 or later

  1. 1. Identify the current version of Algernon being deployed in your environment
  2. 2. Upgrade Algernon to version 1.17.6 or later to obtain the patched binary
  3. 3. Restart the Algernon service to apply the updated version
  4. 4. Verify that uploaded files are now properly restricted within the web root directory

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
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,750
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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-2026-43982 in production — separate from our analysis above.

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What this is

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