How severe is CVE-2025-4366?

CVE-2025-4366 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2025-4366?

CVE-2025-4366 affects the following packages: pingora-core (crates.io). Ecosystems affected: crates.io.

How do I fix CVE-2025-4366?

Update pingora-core to 0.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-4366 is resolved across your whole dependency graph.

How do I detect CVE-2025-4366 in my crates.io dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pingora-core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2025-4366 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2025-4366?

O3 pinpoints whether CVE-2025-4366 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2025-4366 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-4366 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2025-4366?

CVE-2025-4366 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 32th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2025-4366 published, and has it been updated?

CVE-2025-4366 was published on May 22, 2025 and was last updated on April 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2025-4366: Pingora has a Request Smuggling Vulnerability (M…

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk32th percentile-0.20%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

🦀pingora-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

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 Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`pingora-core`	all versions	0.5.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pingora-core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update pingora-core to 0.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-4366 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2025-4366 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2025-4366. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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 t

O3 Security · Impact-Aware SCA

Is CVE-2025-4366 in your dependencies?

O3 detects CVE-2025-4366 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works

CVE-2025-4366