CVE-2024-45614 | Header normalization allows for client to clobber proxy set headers in Puma

Puma is a Ruby/Rack web server built for parallelism. In affected versions clients could clobber values set by intermediate proxies (such as X-Forwarded-For) by providing a underscore version of the same header (X-Forwarded_For). Any users relying on proxy set variables is affected. v6.4.3/v5.6.9 now discards any headers using underscores if the non-underscore version also exists. Effectively, allowing the proxy defined headers to always win. Users are advised to upgrade. Nginx has a underscores_in_headers configuration variable to discard these headers at the proxy level as a mitigation. Any users that are implicitly trusting the proxy defined headers for security should immediately cease doing so until upgraded to the fixed versions.

Published: 2024-09-19 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2024-45614 is rated Low Risk (37.8/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.65%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2024-45614

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-26 0.66% 0.65% -0.01%
2 2026-06-15 0.80% 0.66% -0.14%
3 2026-05-11 — 0.80% —

Full EPSS history (19 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2024-45614

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.4 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 2.7 [email protected]
5.4 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 2.7 [email protected]

Weakness enumeration for CVE-2024-45614

GitHub Security Advisory for CVE-2024-45614

GHSA-9hf4-67fc-4vf4 · Severity: medium · Ecosystem: rubygems — Puma's header normalization allows for client to clobber proxy set headers

OS Trackers for CVE-2024-45614

vendor priority summary link
debian not yet assigned CVE-2024-45614 not yet assigned priority: Debian including 1 source packages (puma), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2024-45614
redhat medium — https://access.redhat.com/security/cve/CVE-2024-45614
suse medium — https://www.suse.com/security/cve/CVE-2024-45614/
ubuntu medium CVE-2024-45614 medium priority: Ubuntu including 1 source packages (puma), 7 status rows across 7 suites (focal, jammy, noble, oracular, plucky, questing, upstream): released 7. https://ubuntu.com/security/CVE-2024-45614

Affected software / configurations for CVE-2024-45614

Vendor Product Version Raw CPE
puma puma < 5.6.9 cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:*
puma puma >= 6.0.0, < 6.4.3 cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:*

References for CVE-2024-45614

cvelogic Threat Intelligence