CVE-2026-2833
HTTP Request Smuggling in Pingora Proxy Enables Session Hijacking
Publication date: 2026-03-05
Last updated on: 2026-03-12
Assigner: Cloudflare, Inc.
Description
Description
CVSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| cloudflare | pingora | to 0.8.0 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-444 | The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability is an HTTP request smuggling issue found in Pingora's handling of HTTP/1.1 connection upgrades. When a Pingora proxy processes a request containing an Upgrade header, it prematurely forwards the remaining bytes on the connection to the backend before the backend has accepted the upgrade. This allows an attacker to send a malicious payload directly to the backend, which may be interpreted as a subsequent request header. As a result, the attacker can bypass proxy-level security controls and potentially hijack sessions across users.
How can this vulnerability impact me? :
This vulnerability primarily impacts standalone Pingora deployments exposed to external traffic. An attacker exploiting this flaw could:
- Bypass proxy-level access control lists (ACL) and web application firewall (WAF) logic.
- Poison caches and upstream connections, causing legitimate users to receive responses intended for smuggled requests.
- Perform cross-user attacks by hijacking sessions or smuggling requests that appear to come from the trusted proxy IP.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, Pingora users should upgrade to Pingora version 0.8.0 or higher.
As a workaround, users may configure their request filter logic to return an error on requests containing the Upgrade header. This prevents processing bytes beyond the request header and disables downstream connection reuse, thereby mitigating the vulnerability.