CVE-2024-45614Network attack vector

Proxy-header overwrite via underscore normalization

Published Sep 19, 2024 · Updated Nov 3, 2025

Header normalization in Puma before 5.6.9 and 6.0.0 through 6.4.2 allows remote attackers to overwrite proxy-set headers. The HTTP parser preserves an underscore-bearing header under a temporary key, and req_env_post_parse previously normalized that key over the proxy's existing Rack environment value. Exploitation requires a deployment that trusts security-relevant proxy headers; attacker-controlled values can redirect responses or weaken HTTPS handling.

CVSS severity5.9
Medium
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Header normalization in Puma before 5.6.9 and 6.0.0 through 6.4.2 allows remote attackers to overwrite proxy-set headers. The HTTP parser preserves an underscore-bearing header under a temporary key, and req_env_post_parse previously normalized that key over the proxy's existing Rack environment value. Exploitation requires a deployment that trusts security-relevant proxy headers; attacker-controlled values can redirect responses or weaken HTTPS handling.

The record

CVE
CVE-2024-45614
Published
Sep 19, 2024
Updated
Nov 3, 2025
Vendor
Puma
Product
Puma
Classifications
CWE-639, CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 19, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 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.

  1. Affected versionversion=< 5.6.9
  2. Affected versionversion=>= 6.0.0, < 6.4.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Puma · Pumaversion=< 5.6.9; version=>= 6.0.0, < 6.4.3

Published CVSS scores

5.9GitHub Security AdvisoryCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
5.4NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-639Authorization Bypass Through User-Controlled Key
CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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