CVE-2023-28846
Denial of Service in unpoly-rails
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
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.
Timeline
ID reserved
By GitHub_M
- 6 days later
· 6 days later
Published
- 23 months later
· 23 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium5.9 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 1.0% · top 36% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.9.
Weakness
Affected products
- affected < 2.7.2.2
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- RubyGemsunpoly-railsGHSA-m875-3xf6-mf78 (opens in a new tab)
References (7)
- https://github.com/unpoly/unpoly-rails/security/advisories/GHSA-m875-3xf6-mf78 (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://github.com/unpoly/unpoly-rails/commit/cd9ad0007daceeb3b2354fdcab4f88350427bf16 (opens in a new tab)x_refsource_MISCx_transferred
- https://docs.nginx.com/nginx/admin-guide/load-balancer/http-health-check/#passive-health-checks (opens in a new tab)x_refsource_MISCx_transferred
- https://github.com/unpoly/unpoly-rails/ (opens in a new tab)x_refsource_MISCx_transferred
- https://makandracards.com/operations/537537-nginx-proxy-buffer-tuning (opens in a new tab)x_refsource_MISCx_transferred
- https://tryhexadecimal.com/guides/http/414-request-uri-too-long (opens in a new tab)x_refsource_MISCx_transferred
- https://unpoly.com/up.protocol (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-m875-3xf6-mf78 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2023-28846)Record last updated .