{"id":"CVE-2026-47737","aliases":["GHSA-2vqw-3mp8-cgmx"],"title":"Puma PROXY Protocol v1 Accepts Repeated Protocol Headers on Persistent Connections","summary":"Puma PROXY Protocol v1 Accepts Repeated Protocol Headers on Persistent Connections","severity":"high","cvss":7.5,"cwe":["CWE-290","CWE-345"],"vendor":"puma","product":"puma","ecosystem":"rubygems","affected":["puma >= 8.0.0, < 8.0.2","puma >= 5.5.0, < 7.2.1"],"patched":["puma 8.0.2","puma 7.2.1"],"published":"2026-06-09","updated":"2026-06-09","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-2vqw-3mp8-cgmx","references":[{"url":"https://github.com/puma/puma/security/advisories/GHSA-2vqw-3mp8-cgmx"},{"url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/puma/CVE-2026-47737.yml"},{"url":"https://www.cve.org/CVERecord/SearchResults?query=CVE-2026-47737"},{"url":"https://github.com/advisories/GHSA-2vqw-3mp8-cgmx"}],"tags":["ghsa","rubygems"],"ingestedAt":"2026-07-07T15:41:59.608Z","epss":0.00266,"epssPercentile":0.18728,"slug":"CVE-2026-47737","body":"## Overview\n\n### Impact\n\nPuma is vulnerable to source IP spoofing when `set_remote_address proxy_protocol: :v1` is enabled and persistent connections are used.\n\nPROXY protocol v1 is a connection-level protocol. [Support was added to Puma in v5.5.0](https://github.com/puma/puma/issues/2651). A proxy sends one PROXY header at the beginning of a TCP connection, before any HTTP data. Puma incorrectly re-parsed PROXY protocol headers after each keep-alive request on the same connection. An attacker able to send HTTP requests through a trusted proxy could therefore inject a second PROXY header between HTTP requests. Puma would treat the injected header as authoritative for the next request and overwrite `REMOTE_ADDR`.\n\nThis can mislead applications or middleware that use `REMOTE_ADDR` for security decisions, rate limiting, auditing, or allow/deny lists.\n\n**Only deployments that explicitly enable PROXY protocol v1 are affected**, and will have set:\n\n```ruby\nset_remote_address proxy_protocol: :v1\n```\n\nPuma's default configuration is not affected. Deployments that do not use persistent connections to Puma are also not expected to be affected by this issue.\n\n### Patches\n\nUsers should upgrade to versions 7.2.1 or 8.0.2.\n\n### Workarounds\n\nDisable PROXY protocol v1 parsing if it is not required:\n\n ```ruby\n   # remove/comment this:\n   # set_remote_address proxy_protocol: :v1\n ```\n\nUsers can also disable persistent connections to Puma, for example:\n\n```ruby\nenable_keep_alives false\n```\n\n### References\n\n- [HAProxy PROXY protocol specification](https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt)\n- [CVE-2025-31135 / GHSA-c2c3-pqw5-5p7c: go-guerrilla repeated PROXY command source IP spoofing](https://github.com/phires/go-guerrilla/security/advisories/GHSA-c2c3-pqw5-5p7c)\n- [Puma `set_remote_address` documentation](https://github.com/puma/puma/blob/master/lib/puma/dsl.rb)\n\n## Affected packages\n\n- `puma >= 8.0.0, < 8.0.2`\n- `puma >= 5.5.0, < 7.2.1`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `puma 8.0.2`\n- `puma 7.2.1`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}