CVE-2020-36939
Published: 27 January 2026
Summary
CVE-2020-36939 is a high-severity Path Traversal (CWE-22) vulnerability in Rubygems (inferred from references). Its CVSS base score is 8.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 17.4% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 CM-6 (Configuration Settings) and SI-10 (Information Input Validation).
Deeper analysis
CVE-2020-36939 is a directory traversal vulnerability (CWE-22) in Cassandra Web version 0.5.0, a Ruby gem providing a web interface for Apache Cassandra databases. The flaw stems from the disabled Rack::Protection module, which allows attackers to manipulate path traversal parameters and read arbitrary files on the server.
Unauthenticated remote attackers can exploit this vulnerability over the network with low complexity and no user interaction required. Successful exploitation enables reading sensitive system files, such as /etc/passwd, and retrieving Apache Cassandra database credentials, resulting in a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).
Mitigation details and advisories are available in referenced sources, including the Vulncheck advisory at https://www.vulncheck.com/advisories/cassandra-web-remote-file-read, an Exploit-DB entry at https://www.exploit-db.com/exploits/49362, the project GitHub repository at https://github.com/avalanche123/cassandra-web, and version information at https://rubygems.org/gems/cassandra-web/versions/0.5.0.
A public exploit is documented on Exploit-DB, highlighting the risk of real-world abuse against exposed Cassandra Web 0.5.0 instances.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2020-30857
Vulnerability details
Cassandra Web 0.5.0 contains a directory traversal vulnerability that allows unauthenticated attackers to read arbitrary files by manipulating path traversal parameters. Attackers can exploit the disabled Rack::Protection module to read sensitive system files like /etc/passwd and retrieve Apache Cassandra database…
more
credentials.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Directory traversal in public-facing web app directly enables remote unauthenticated file read (T1190 initial access), arbitrary local file access (T1005), and retrieval of credentials from files like /etc/passwd (T1552.001).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
SI-10 requires validating user-supplied inputs to prevent directory traversal attacks by rejecting or sanitizing path manipulation parameters like '../' sequences.
CM-6 ensures secure baseline configuration settings, such as enabling the Rack::Protection module, to block the directory traversal vulnerability in Cassandra Web.
AC-3 enforces approved authorizations for accessing system resources, limiting the impact of successful directory traversal by restricting file read permissions.