{"id":"CVE-2026-46369","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-46369","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 > 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 < B < 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","published":"2026-08-12T15:16:53Z","modified":"2026-08-12T15:30:08.785311592Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"crates.io","name":"nimiq-blockchain","fixedVersion":"1.5.1"}],"fix":{"url":"https://github.com/nimiq/core-rs-albatross/pull/3772","label":"nimiq/core-rs-albatross#3772"},"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"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T15:30:08.785311592Z"}}