{"id":"GHSA-3763-qp59-59vf","summary":"nimiq-blockchain: Validity store off by one error","details":"### Impact\nThe validity store treats a transaction with stored `block_number = X` as \"in window\" only when `X \u003e last_bn - transaction_validity_window_blocks` (strict inequality). However the protocol's `Transaction::is_valid_at` accepts a transaction for inclusion in any block in `[validity_start_height - blocks_per_batch, validity_start_height + window - 1]`. By choosing `validity_start_height = X + blocks_per_batch` (the largest value still compatible with first inclusion at block X), an attacker can replay the same signed transaction in any block B such that `X + window \u003c B \u003c validity_start_height + window`, i.e., a contiguous window of `blocks_per_batch - 1` blocks (59 on MainNet, ~10 minutes) during which the replay-protection check fails to flag it. The same transaction is then executed twice: the sender is debited twice, the recipient credited twice.\n\n### Patches\nhttps://github.com/nimiq/core-rs-albatross/pull/3772\n\n### Workarounds\nNo known workarounds","aliases":["CVE-2026-46369"],"modified":"2026-08-12T15:41:12.067694Z","published":"2026-08-12T15:16:53Z","database_specific":{"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-08-12T15:16:53Z","nvd_published_at":null,"cwe_ids":["CWE-193","CWE-294"]},"references":[{"type":"WEB","url":"https://github.com/nimiq/core-rs-albatross/security/advisories/GHSA-3763-qp59-59vf"},{"type":"WEB","url":"https://github.com/nimiq/core-rs-albatross/pull/3772"},{"type":"WEB","url":"https://github.com/nimiq/core-rs-albatross/commit/a530b2434ebca6e3716f07c73079786fcc6f2e41"},{"type":"PACKAGE","url":"https://github.com/nimiq/core-rs-albatross"}],"affected":[{"package":{"name":"nimiq-blockchain","ecosystem":"crates.io","purl":"pkg:cargo/nimiq-blockchain"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.5.1"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 1.5.0","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-3763-qp59-59vf/GHSA-3763-qp59-59vf.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"}]}