CVE-2026-2833

Description

Pingora versions prior to 0.8.0 would immediately forward bytes following a request with an Upgrade header to the backend, without waiting for a 101 Switching Protocols response. This allows an attacker to smuggle requests to the backend and bypass proxy-level security controls. This vulnerability primarily affects standalone Pingora deployments where a Pingora proxy is exposed to external traffic. An attacker could exploit this to bypass proxy-level ACL controls and WAF logic, poison caches and upstream connections, or perform cross-user attacks by hijacking sessions. This flaw was corrected in commit 824bdeefc61e121cc8861de1b35e8e8f39026ecd by only switching connection modes after receiving a 101 response from the backend. Users should upgrade to Pingora >= 0.8.0. Note: Cloudflare customers and Cloudflare's CDN infrastructure were not affected by this vulnerability, as ingress proxies in the CDN stack maintain proper HTTP parsing boundaries and do not prematurely switch to upgraded connection forwarding mode.

How to fix CVE-2026-2833

To remediate CVE-2026-2833, upgrade the affected package to a fixed version below.

• —upgrade to 0.8.0 or later
• —upgrade to 0.8.0 or later

Is CVE-2026-2833 being exploited?

Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 0.8.0
• >= 0.0.0-0, < 0.8.0

CVSS scores

References (6)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2026-2833
• PATCHcrates.io/crates/pingora-core
• PATCHgithub.com/cloudflare/pingora
• WEBblog.cloudflare.com/pingora-oss-smuggling-vulnerabilities/
• WEB