CVE-2026-2833 (GCVE-0-2026-2833)

Vulnerability from cvelistv5 – Published: 2026-03-04 23:20 – Updated: 2026-03-04 23:20
VLAI?
Title
HTTP Request Smuggling via Premature Upgrade
Summary
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.
CWE
  • CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Assigner
Impacted products
Credits
Rajat Raghav (xclow3n)
Show details on NVD website

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              "value": "\u003cspan style=\"background-color: transparent;\"\u003eAn HTTP request smuggling vulnerability (CWE-444) was found in Pingora\u0027s 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.\u003cbr\u003e\u003cbr\u003e\u003c/span\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003eImpact\u003c/span\u003e\u003c/p\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003eThis vulnerability primarily affects standalone Pingora deployments where a Pingora proxy is exposed to external traffic. An attacker could exploit this to:\u003c/span\u003e\u003c/p\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003eBypass proxy-level ACL controls and WAF logic\u003c/span\u003e\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003ePoison caches and upstream connections, causing subsequent requests from legitimate users to receive responses intended for smuggled requests\u003c/span\u003e\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003ePerform cross-user attacks by hijacking sessions or smuggling requests that appear to originate from the trusted proxy IP\u003c/span\u003e\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003eCloudflare\u0027s 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.\u003c/span\u003e\u003c/p\u003e\u003cbr\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003eMitigation:\u003c/span\u003e\u003c/p\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003ePingora users should upgrade to Pingora v0.8.0 or higher\u003c/span\u003e\u003cspan style=\"background-color: transparent;\"\u003e\u003cbr\u003e\u003c/span\u003e\u003c/p\u003e\u003cb\u003e\u003c/b\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003eAs 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.\u003c/span\u003e\u003c/p\u003e"
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