---
id: CVE-2026-105299
aliases:
  - RUSTSEC-2026-0390
  - GHSA-vx4q-2c55-cvmg
title: >-
  Pingora forwards client-nominated Connection headers to HTTP/1 upstreams,
  allowing ACL bypass in specific chained deployments
summary: >-
  Pingora forwards client-nominated Connection headers to HTTP/1 upstreams,
  allowing ACL bypass in specific chained deployments
severity: high
cvss: 8.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N'
vendor: pingora-proxy
product: pingora-proxy
ecosystem: rust
affected:
  - 'pingora-proxy >= 0.0.0-0, < 0.9.0'
patched:
  - pingora-proxy 0.9.0
published: '2026-10-20'
updated: '2026-10-26'
sourceUpdated: '2026-10-26T11:15:11.361865763Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/RUSTSEC-2026-0390'
references:
  - url: 'https://crates.io/crates/pingora-proxy'
  - url: 'https://rustsec.org/advisories/RUSTSEC-2026-0390.html'
  - url: >-
      https://github.com/cloudflare/pingora/commit/28c18e6b6b04dd0bd937234e5950049e6d74cded
  - url: >-
      https://github.com/cloudflare/pingora/commit/ca23f1668eca8e78be7ba62ef0edbd458b40eeee
  - url: 'https://github.com/cloudflare/pingora'
tags:
  - osv
  - rust
  - cve.org
epss: 0.00425
epssPercentile: 0.36596
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-20T19:18:45.445676Z'
cvssSource: cna
ingestedAt: '2026-10-20T01:49:42.583Z'
---

## Overview

Pingora versions prior to 0.9.0 passed the downstream request through `upstream_request_filter` and wrote it to HTTP/1 upstreams without removing the client's Connection header, other hop-by-hop headers, or the headers Connection nominated, although RFC 9110 Section 7.6.1 requires intermediaries to remove them. The HTTP/2 upstream path already removed Connection and related HTTP/1-specific headers. A client could therefore nominate a header that the application adds in `upstream_request_filter` (for example, `Connection: keep-alive, X-Forwarded-For`). A downstream HTTP/1 intermediary that honors Connection would then strip the Pingora-added header before it reached the origin.

This specifically affects chained deployments where an HTTP/1 intermediary between Pingora and the origin processes Connection nominations (for example, Go's `net/http/httputil.ReverseProxy`) and the origin trusts headers added by that intermediary (for example, X-Forwarded-For for IP-based authorization). A remote, unauthenticated attacker can have those headers removed, potentially bypassing authorization. This is the same class of issue as CVE-2022-31813 in Apache HTTP Server.

This flaw was corrected in commits 28c18e6b6b04dd0bd937234e5950049e6d74cded and ca23f1668eca8e78be7ba62ef0edbd458b40eeee. By default, Pingora now removes hop-by-hop and Connection-nominated headers from upstream requests, and rejects requests whose Connection header nominates Host, X-Forwarded-For, X-Forwarded-Host, X-Forwarded-Proto, or a pseudo-header. This is controlled by `PeerOptions::http_upstream_request_policy`; `HttpUpstreamRequestPolicy::preserve()` restores the old passthrough behavior and should not be used if the origin relies on headers added by Pingora. Users should upgrade to Pingora >= 0.9.0.

Note: Cloudflare CDN customers were unaffected, as no such chained deployment as described above exists with internal Pingora services, and Connection headers are sanitized before arriving at Pingora gateways.

## Affected packages

- `pingora-proxy >= 0.0.0-0, < 0.9.0`

## Remediation

Upgrade to a patched release:

- `pingora-proxy 0.9.0`