What is the CVSS score of CVE-2026-2833?

CVE-2026-2833 has a CVSS 3.1 base score of 9.1 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. EPSS exploitation probability: 0.1%.

Which versions of Pingora are affected by CVE-2026-2833?

A critical HTTP request smuggling vulnerability in Pingora (CVSS 9.1) allows attackers to bypass security controls and potentially execute unauthorized actions.. A patch is available.

How to fix or mitigate CVE-2026-2833?

Within 24 hours: Inventory all systems running Pingora and assess exposure; enable enhanced monitoring for suspicious HTTP patterns. Within 7 days: Implement network segmentation to limit Pingora exposure; deploy WAF rules blocking malformed HTTP/1.1 upgrade requests; consider disabling HTTP upgrade functionality if not business-critical. Within 30 days: Prioritize vendor patch deployment immediately upon release; conduct forensic analysis for signs of exploitation.

Pingora CVE-2026-2833

CRITICAL

HTTP Request/Response Smuggling (CWE-444)

2026-03-05 cna@cloudflare.com

GHSA-xq2h-p299-vjwv

Code Injection Pingora Cloudflare

9.1

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

9.1 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Lifecycle Timeline

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

Analysis Generated

Mar 12, 2026 - 22:06 vuln.today

CVE Published

Mar 05, 2026 - 00:15 nvd

CRITICAL 9.1

DescriptionCVE.org

An HTTP request smuggling vulnerability (CWE-444) was found in Pingora's handling of HTTP/1.1 connection upgrades. The issue occurs when a Pingora proxy reads a request containing an Upgrade header, causing the proxy to pass through the rest of the bytes on the connection to a backend before the backend has accepted the upgrade. An attacker can thus directly forward a malicious payload after a request with an Upgrade header to that backend in a way that may be interpreted as a subsequent request header, bypassing proxy-level security controls and enabling cross-user session hijacking.

Impact

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, causing subsequent requests from legitimate users to receive responses intended for smuggled requests
Perform cross-user attacks by hijacking sessions or smuggling requests that appear to originate from the trusted proxy IP

Cloudflare's CDN infrastructure was 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.

Mitigation:

Pingora users should upgrade to Pingora v0.8.0 or higher

As a workaround, users may return an error on requests with the Upgrade header present in their request filter logic in order to stop processing bytes beyond the request header and disable downstream connection reuse.