Vulnerability · Published Mar 30, 2023 · Assigned by GitHub_M
CVE-2023-28846Denial of Service in unpoly-rails
Medium 5.9
In plain English
A medium-severity uncontrolled resource consumption in unpoly-rails from unpoly. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.0% (higher than 64% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Unpoly is a JavaScript framework for server-side web applications. There is a possible Denial of Service (DoS) vulnerability in the `unpoly-rails` gem that implements the Unpoly server protocol for Rails applications. 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. This issue has been fixed and released as version 2.7.2.2 which is available via RubyGems and GitHub. Users unable to upgrade may: 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; or instead of changing your server configuration you may also configure your Rails application to delete redundant `X-Up-Location` headers set by unpoly-rails.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| RubyGems | unpoly-rails | 2.7.2.2 | GHSA-m875-3xf6-mf78 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| unpoly | unpoly-rails | < 2.7.2.2 |
Weakness: CWE-400 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/unpoly/unpoly-rails/security/advisories/GHSA-m875-3xf6-mf78 x_refsource_CONFIRM
- https://github.com/unpoly/unpoly-rails/commit/cd9ad0007daceeb3b2354fdcab4f88350427bf16 x_refsource_MISC
- https://docs.nginx.com/nginx/admin-guide/load-balancer/http-health-check/#passive-health-checks x_refsource_MISC
- https://github.com/unpoly/unpoly-rails/ x_refsource_MISC
- https://makandracards.com/operations/537537-nginx-proxy-buffer-tuning x_refsource_MISC
- https://tryhexadecimal.com/guides/http/414-request-uri-too-long x_refsource_MISC
- https://unpoly.com/up.protocol x_refsource_MISC