---
title: "CVE-2026-2833: Pingora vulnerable to HTTP Request Smuggling via Premature Upgrade"
url: https://erroneo.us/security/cve/CVE-2026-2833/
description: "CVE-2026-2833 (pingora-core (crates.io (Rust))): An HTTP request smuggling vulnerability (CWE-444) was found in Pingora's handling of HTTP/1.1 connection…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-03-04
date_modified: 2026-03-09
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-2833"
kev: false
cvss: 9.3
epss: 0.00534
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-2833: Pingora vulnerable to HTTP Request Smuggling via Premature Upgrade

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.5% , percentile 44: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 44% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes pingora-core (crates.io (Rust)) <= 0.7.0, fixed in 0.8.0 . Check your lockfile, including transitive dependencies.

## What it is

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.

## Affected packages

- crates.io (Rust) `pingora-core` <= 0.7.0 → fixed: 0.8.0

## Affected products (CVE record)

- Cloudflare https://github.com/cloudflare/pingora: < 0.8.0

## Severity

- cloudflare CVSS 4.0: 9.3 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N`
- GitHub CVSS 4.0: 9.3 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact partial .
- FIRST EPSS (model of 2026-10-21): 0.53% probability of exploitation activity in the next 30 days; percentile 44.

## Sources

- [GitHub Advisory GHSA-xq2h-p299-vjwv](https://github.com/advisories/GHSA-xq2h-p299-vjwv)
- [CVE.org record CVE-2026-2833](https://www.cve.org/CVERecord?id=CVE-2026-2833)
- [NVD entry CVE-2026-2833](https://nvd.nist.gov/vuln/detail/CVE-2026-2833)
- [github.com](https://github.com/cloudflare/pingora)
- [github.com](https://github.com/cloudflare/pingora/security/advisories/GHSA-xq2h-p299-vjwv)
- [rustsec.org](https://rustsec.org/advisories/RUSTSEC-2026-0033.html)

---
Source page: https://erroneo.us/security/cve/CVE-2026-2833/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt