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OpenAdvisories
High ALAS2-2025-2856 1 CVE

Important: pcs security update (Amazon Linux 2)

Published May 21, 2025 · Updated May 29, 2025

Summary

Package updates are available for Amazon Linux 2 that fix the following vulnerabilities: CVE-2025-46727: Rack is a modular Ruby web server interface. Prior to versions 2.2.14, 3.0.16, and 3.1.14, `Rack::QueryParser` parses query strings and `application/x-www-form-urlencoded` bodies into Ruby data structures without imposing any limit on the number of parameters, allowing attackers to send requests with extremely large numbers of parameters. The vulnerability arises because `Rack::QueryParser` iterates over each `&`-separated key-value pair and adds it to a Hash without enforcing an upper bound on the total number of parameters. This allows an attacker to send a single request containing hundreds of thousands (or more) of parameters, which consumes excessive memory and CPU during parsing. An attacker can trigger denial of service by sending specifically crafted HTTP requests, which can cause memory exhaustion or pin CPU resources, stalling or crashing the Rack server. This results in full service disruption until the affected worker is restarted. Versions 2.2.14, 3.0.16, and 3.1.14 fix the issue. Some other mitigations are available. One may use middleware to enforce a maximum query string size or parameter count, or employ a reverse proxy (such as Nginx) to limit request sizes and reject oversized query strings or bodies. Limiting request body sizes and query string lengths at the web server or CDN level is an effective mitigation.

Fixed packages 3

ReleasePackageFixed in
Amazon Linux · 2 pcs 0:0.9.169-3.amzn2.3.0.6
Amazon Linux · 2 pcs-debuginfo 0:0.9.169-3.amzn2.3.0.6
Amazon Linux · 2 pcs-snmp 0:0.9.169-3.amzn2.3.0.6

Vulnerabilities 1

  • High 7.5

    Unbounded-Parameter DoS in Rack::QueryParser

    Rack is a modular Ruby web server interface. Prior to versions 2.2.14, 3.0.16, and 3.1.14, `Rack::QueryParser` parses query strings and `application/x-www-form-urlencoded` bodies into Ruby data structures without imposing any limit on the number of parameters…

References

  • web
    https://alas.aws.amazon.com/cve/html/CVE-2025-46727.html