CVE-2025-4366: Request Smuggling Vulnerability in Pingora

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-05-22 · updated 2026-06-17
Weakness: CWE-444

Description

A request smuggling vulnerability identified within Pingora’s proxying framework, pingora-proxy, allows malicious HTTP requests to be injected via manipulated request bodies on cache HITs, leading to unauthorized request execution and potential cache poisoning. Fixed in: https://github.com/cloudflare/pingora/commit/fda3317ec822678564d641e7cf1c9b77ee3759ff https://github.com/cloudflare/pingora/commit/fda3317ec822678564d641e7cf1c9b77ee3759ff Impact: The issue could lead to request smuggling in cases where Pingora’s proxying framework, pingora-proxy, is used for caching allowing an attacker to manipulate headers and URLs in subsequent requests made on the same HTTP/1.1 connection.

Affected products

Cloudflare https://github.com/cloudflare/pingora: before 0.5.0 — fixed in 0.5.0

How to fix

Upgrade to a fixed version: Cloudflare https://github.com/cloudflare/pingora 0.5.0. Check the vendor advisory for mitigations.

References

https://github.com/cloudflare/pingora

Get alerted when CVE-2025-4366 or the next vulnerability affects your stack