CVE intelligence and bounded remediation

CVE-2021-21269 — Keymaker is a Mastodon Community Finder based Matrix Community serverlist page Server

High CVSS 7.7

Keymaker is a Mastodon Community Finder based Matrix Community serverlist page Server. In Keymaker before version 0.2.0, the assets endpoint did not check for the extension. The rust `join` method without checking user input might have made it abe to do a Path Traversal attack causing to read more files than allowed. This is fixed in version 0.2.0.

Severity
High
CVSS
7.7 (3.1)
Published
2021-01-20
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-22

Affected products

  • keymaker_project / keymaker

Matched remediation archetype

Path traversal, unsafe upload, and file handling

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Trace untrusted filenames, archive entries, URLs, and path segments into read, write, include, extraction, and upload operations.
  • Identify filesystem roots, mount permissions, symbolic-link behavior, archive handling, and whether uploaded content is web-accessible or executable.
  • Review canonicalization and containment checks across supported operating systems and storage backends.

Remediate safely

  • Generate server-side storage identifiers and resolve paths beneath a fixed root using filesystem-aware containment checks.
  • Reject absolute, parent-relative, alternate-separator, device, link, and archive entries that escape the intended root.
  • Store uploads outside executable or served paths, validate type and size, and use private atomic temporary files.

Authoritative sources

Complete CVE record and remediation plan

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