{"id":"CVE-2026-70658","aliases":["GHSA-mjgf-xj26-9qf9"],"url":"https://o3.security/vulnerability/CVE-2026-70658","summary":"pay-rails/pay: non-constant-time HMAC comparison in Paddle Billing webhook signature verifier","details":"Pay is a payments engine for Ruby on Rails 6.0 and higher. Prior to 11.6.2, Pay::Webhooks::PaddleBillingController#valid_signature? in app/controllers/pay/webhooks/paddle_billing_controller.rb compares the computed 64-character SHA-256 HMAC with the attacker-controlled h1 token from the Paddle-Signature header using Ruby String#==. An unauthenticated remote attacker who can repeatedly submit requests to /pay/webhooks/paddle_billing and obtain sufficiently precise timing measurements can infer matching digest prefixes and recover a valid signature. A forged accepted webhook is enqueued through Pay::Webhooks::ProcessJob and can cause a host application to update billing state, provision paid features, record refunds, or trigger customer notifications. This issue is fixed in version 11.6.2.","published":"2026-09-14T17:14:57.207Z","modified":"2026-09-16T03:47:20.365894611Z","cvss":{"score":7.4,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"RubyGems","name":"pay","fixedVersion":null}],"fix":{"url":"https://github.com/pay-rails/pay/commit/ba6494109d88209fba2a4df2d9d6373fe81ed805","label":"pay-rails/pay@ba64941"},"references":[{"type":"WEB","url":"https://github.com/pay-rails/pay/releases/tag/v11.6.2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/70xxx/CVE-2026-70658.json"},{"type":"ADVISORY","url":"https://github.com/pay-rails/pay/security/advisories/GHSA-mjgf-xj26-9qf9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-70658"},{"type":"FIX","url":"https://github.com/pay-rails/pay/commit/ba6494109d88209fba2a4df2d9d6373fe81ed805"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-16T03:47:20.365894611Z"}}