Request hijacking and cache poisoning via undrained bodies
Published May 22, 2025 · Updated Jun 18, 2025
HTTP request smuggling in Cloudflare Pingora before 0.5.0 allows remote attackers to alter subsequent proxy requests on cache hits. On a cache hit, pingora-proxy returns the cached response without draining the declared HTTP/1.1 request body before reusing the downstream connection, so unread bytes prefix the next request. Exploitation requires caching, a cache hit, connection reuse, and a later request; injected headers or URLs can poison cached content or redirect traffic and disclose visited URLs.
Summary
What happened
HTTP request smuggling in Cloudflare Pingora before 0.5.0 allows remote attackers to alter subsequent proxy requests on cache hits. On a cache hit, pingora-proxy returns the cached response without draining the declared HTTP/1.1 request body before reusing the downstream connection, so unread bytes prefix the next request. Exploitation requires caching, a cache hit, connection reuse, and a later request; injected headers or URLs can poison cached content or redirect traffic and disclose visited URLs.
The record
- CVE
- CVE-2025-4366
- Published
- May 22, 2025
- Updated
- Jun 18, 2025
- Vendor
- Cloudflare
- Product
- Pingora
- Classifications
- CWE-444, CAPEC-33, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 22, 2025CVE publishedPublication date reported by the CVE source.
- Jun 18, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <0.5.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Cloudflare cache-hit request-smuggling exampleproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo