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Security Advisories: GSA_kwCzR0hTQS1tODc1LTN4ZjYtbWY3OM4AAyeB
unpoly-rails Denial of Service vulnerability
There is a possible Denial of Service (DoS) vulnerability in the unpoly-rails gem that implements the Unpoly server protocol for Rails applications.
Impact
This issues affects Rails applications that operate as an upstream of a load balancer's that uses passive health checks.
The unpoly-rails gem echoes the request URL as an X-Up-Location
response header. By making a request with exceedingly long URLs (paths or query string), an attacker can cause unpoly-rails to write a exceedingly large response header.
If the response header is too large to be parsed by a load balancer downstream of the Rails application, it may cause the load balancer to remove the upstream from a load balancing group. This causes that application instance to become unavailable until a configured timeout is reached or until an active healthcheck succeeds.
Patches
The fixed release 2.7.2.2+ is available via RubyGems and GitHub.
Workarounds
If you cannot upgrade to a fixed release, several workarounds are available:
-
Configure your load balancer to use active health checks, e.g. by periodically requesting a route with a known response that indicates healthiness.
-
Configure your load balancer so the maximum size of response headers is at least twice the maximum size of a URL.
-
Instead of changing your server configuration you may also configure your Rails application to delete redundant
X-Up-Location
headers set by unpoly-rails:class ApplicationController < ActionController::Base after_action :remove_redundant_up_location_header private def remove_redundant_up_location_header if request.original_url == response.headers['X-Up-Location'] response.headers.delete('X-Up-Location') end end end
JSON: https://advisories.ecosyste.ms/api/v1/advisories/GSA_kwCzR0hTQS1tODc1LTN4ZjYtbWY3OM4AAyeB
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Moderate
Classification: General
Published: about 1 year ago
Updated: about 1 year ago
CVSS Score: 5.9
CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Identifiers: GHSA-m875-3xf6-mf78, CVE-2023-28846
References:
- https://github.com/unpoly/unpoly-rails/security/advisories/GHSA-m875-3xf6-mf78
- https://nvd.nist.gov/vuln/detail/CVE-2023-28846
- https://github.com/unpoly/unpoly-rails/commit/cd9ad0007daceeb3b2354fdcab4f88350427bf16
- https://docs.nginx.com/nginx/admin-guide/load-balancer/http-health-check/#passive-health-checks
- https://github.com/unpoly/unpoly-rails/
- https://makandracards.com/operations/537537-nginx-proxy-buffer-tuning
- https://tryhexadecimal.com/guides/http/414-request-uri-too-long
- https://unpoly.com/up.protocol
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/unpoly-rails/CVE-2023-28846.yml
- https://github.com/advisories/GHSA-m875-3xf6-mf78
Blast Radius: 6.1
Affected Packages
rubygems:unpoly-rails
Dependent packages: 0Dependent repositories: 11
Downloads: 246,904 total
Affected Version Ranges: < 2.7.2.2
Fixed in: 2.7.2.2
All affected versions:
All unaffected versions: 0.20.0, 0.21.0, 0.22.0, 0.22.1, 0.23.0, 0.24.0, 0.24.1, 0.25.0, 0.25.1, 0.25.2, 0.26.0, 0.26.1, 0.26.2, 0.27.0, 0.27.1, 0.27.2, 0.27.3, 0.28.0, 0.28.1, 0.29.0, 0.30.0, 0.30.1, 0.31.0, 0.31.1, 0.31.2, 0.32.0, 0.33.0, 0.34.0, 0.34.1, 0.34.2, 0.35.0, 0.35.1, 0.35.2, 0.36.0, 0.36.1, 0.36.2, 0.37.0, 0.50.0, 0.50.1, 0.50.2, 0.51.0, 0.51.1, 0.52.0, 0.53.0, 0.53.1, 0.53.2, 0.53.3, 0.53.4, 0.54.0, 0.54.1, 0.55.0, 0.55.1, 0.56.0, 0.56.1, 0.56.2, 0.56.3, 0.56.4, 0.56.5, 0.56.6, 0.56.7, 0.57.0, 0.60.0, 0.60.1, 0.60.2, 0.60.3, 0.61.0, 0.61.1, 0.62.0, 0.62.1, 1.0.0, 1.0.1, 1.0.3, 2.0.0, 2.0.1, 2.1.0, 2.2.0, 2.2.1, 2.3.0, 2.4.0, 2.4.1, 2.5.0, 2.5.1, 2.5.2, 2.5.3, 2.6.0, 2.6.1, 2.7.1, 2.7.2, 3.0.0, 3.1.0, 3.1.1, 3.2.0, 3.2.1, 3.2.2, 3.3.0, 3.5.0, 3.5.1, 3.5.2, 3.6.0, 3.6.1, 3.7.0, 3.7.1, 3.7.2, 3.7.3