{"id":"GHSA-pf4j-pf3w-95f9","summary":"nimiq-transaction: UpdateValidator transactions allows voting key change without proof-of-knowledge","details":"### Impact\nThe staking contract accepts `UpdateValidator` transactions that set `new_voting_key=Some(...)` while omitting `new_proof_of_knowledge`. this skips the proof-of-knowledge requirement that is needed to prevent BLS rogue-key attacks when public keys are aggregated.\n\nBecause tendermint macro block justification verification aggregates validator voting keys and verifies a single aggregated BLS signature against that aggregate public key, a rogue-key voting key in the validator set can allow an attacker to forge a quorum-looking justification while only producing a single signature.\n\nWhile the impact is critical, the exploitability is low: The voting keys are fixed for the epoch, so the attacker would need to know the next epoch validator set (chosen through VRF), which is unlikely.\n\n### Patches\n[The patch for this vulnerability](https://github.com/nimiq/core-rs-albatross/commit/e7f0ab7d2115e17d6e5548ddc60f10df1a5d645f) is included as part of [v1.3.0](https://github.com/nimiq/core-rs-albatross/releases/tag/v1.3.0).\n\n### Workarounds\nNo known workarounds.","aliases":["CVE-2026-34068"],"modified":"2026-05-05T16:09:54.224832Z","published":"2026-04-22T19:22:53Z","database_specific":{"github_reviewed_at":"2026-04-22T19:22:53Z","nvd_published_at":"2026-04-22T21:17:08Z","cwe_ids":["CWE-347"],"severity":"MODERATE","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/nimiq/core-rs-albatross/security/advisories/GHSA-pf4j-pf3w-95f9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-34068"},{"type":"WEB","url":"https://github.com/nimiq/core-rs-albatross/pull/3654"},{"type":"WEB","url":"https://github.com/nimiq/core-rs-albatross/commit/e7f0ab7d2115e17d6e5548ddc60f10df1a5d645f"},{"type":"PACKAGE","url":"https://github.com/nimiq/core-rs-albatross"},{"type":"WEB","url":"https://github.com/nimiq/core-rs-albatross/releases/tag/v1.3.0"}],"affected":[{"package":{"name":"nimiq-transaction","ecosystem":"crates.io","purl":"pkg:cargo/nimiq-transaction"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"last_affected":"0.2.0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-pf4j-pf3w-95f9/GHSA-pf4j-pf3w-95f9.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N"}]}