Vulnerability in puma (CVE-2026-47737)
Summary
Vulnerability in puma (CVE-2026-47737). Data can be tampered with by attackers. Exploitable via REMOTE_ADDR. Mitigation: upgrade to 7.2.1 or later.
Original description
The description as published by the source.
Puma is a Ruby/Rack web server built for parallelism. From 5.5.0 until 7.2.1 and 8.0.2, Puma is vulnerable to source IP spoofing when set_remote_address proxy_protocol: :v1 is enabled and persistent connections are used because Puma incorrectly re-parses PROXY protocol headers after each keep-alive request on the same connection, allowing an attacker to inject a second PROXY header and overwrite REMOTE_ADDR. This issue is fixed in versions 7.2.1 and 8.0.2.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-47737 has been found in puma.
Attackers can target a specific entry point like REMOTE_ADDR over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 7.5/10.
What to do: upgrade puma to 7.2.1 or later.
If unsure, ask your IT team or search "puma CVE-2026-47737" on the vendor's site.
CVE-2026-47737 (puma) — CWE-290 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: REMOTE_ADDR / set_remote_address
Patched: 7.2.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-290) exists in puma. Attackers reach the vulnerable code path via REMOTE_ADDR without authentication.
Check the vendor advisory for the affected versions of puma. Attack surface: REMOTE_ADDR / set_remote_address.
Severity: High (CVSS 7.5/10). Data can be tampered with by attackers.
Update to 7.2.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'puma' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'puma' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
pumaを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade puma to 7.2.1ステージング環境で 7.2.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-47737 puma Fixed in: 5.6.5-3+deb12u2
- Ubuntu UBUNTU-CVE-2026-47737 puma
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- patch github.com
- patch github.com
- patch github.com
- patch github.com
- web github.com
- web cve.org
- web github.com
- web github.com
- web github.com