Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| puma | puma | >= 6.0.0, < 6.4.3, < 5.6.9 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | puma | 6.4.3-1 | — |
| Debian 13 | puma | 6.4.3-1 | — |
| Debian 12 | puma | 5.6.5-3+deb12u1 | — |
| Debian 11 | puma | 4.3.8-1+deb11u3 | DLA-3947-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | puma | 6.4.2-4ubuntu4.3 | USN-7031-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | puma | 5.5.2-2ubuntu2+esm2 | USN-7031-2 |
| Ubuntu Pro 20.04 LTS | puma | 3.12.4-1ubuntu2+esm2 | USN-7031-2 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | rubygem-puma | 5.6.9-150600.18.3.1 | SUSE-SU-2025:03467-1 |
| SLES 15 SP6 | rubygem-puma | 5.6.9-150600.18.3.1 | SUSE-SU-2025:03467-1 |
| SLES 15 SP5 | rubygem-puma | 4.3.12-150000.3.15.1 | SUSE-SU-2025:03466-1, SUSE-SU-2024:3644-1 |
| SLES 15 SP4 | rubygem-puma | 4.3.12-150000.3.15.1 | SUSE-SU-2025:03466-1, SUSE-SU-2024:3644-1 |
| SLES 15 SP3 | rubygem-puma | 4.3.12-150000.3.15.1 | SUSE-SU-2025:03466-1, SUSE-SU-2024:3644-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP2 | rubygem-puma | 4.3.12-150000.3.15.1 | SUSE-SU-2024:3644-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | rubygem-puma | 6.4.3-1.1 | openSUSE-SU-2026:10357-1, openSUSE-SU-2025:15123-1, openSUSE-SU-2024:14474-1 |
| openSUSE Leap 15.6 | rubygem-puma | 5.6.9-150600.18.3.1 | SUSE-SU-2025:03467-1 |
| openSUSE Leap 15.5 | rubygem-puma | 4.3.12-150000.3.15.1 | SUSE-SU-2024:3644-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | gitlab-cng-18.2 | 18.2.1-r1 | — |
| Wolfi rolling | ruby3.2-puma | 6.4.3-r0 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
GitHub 1 repository
-
ooooooo-q/puma_header_normalization-CVE-2024-45614 ★ 0 · Sep 28, 2024
Puma Header normalization CVE-2024-45614 確認
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| RubyGems | puma | < 5.6.9 | 5.6.9 | GHSA-9hf4-67fc-4vf4 |
| RubyGems | puma | >= 6.0.0, < 6.4.3 | 6.4.3 | GHSA-9hf4-67fc-4vf4 |
Advisories 9
- USN-7031-1 puma vulnerability Ubuntu Security Notices (USN) · Apr 27, 2026
- USN-7031-2 puma vulnerability Ubuntu Security Notices (USN) · Apr 27, 2026
- SUSE-SU-2025:03466-1 Security update for rubygem-puma SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:03467-1 Security update for rubygem-puma SUSE / openSUSE Security Updates · Mar 23, 2026
- openSUSE-SU-2026:10357-1 ruby4.0-rubygem-puma-6.4.3-1.5 on GA media SUSE / openSUSE Security Updates · Mar 14, 2026
- DLA-3947-1 puma - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2024:3644-1 Security update for rubygem-puma SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2025:15123-1 ruby3.4-rubygem-puma-6.4.3-1.3 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:14474-1 ruby3.3-rubygem-puma-6.4.3-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026