{"id":"CVE-2020-25576","aliases":["GHSA-mmc9-pwm7-qj5w","RUSTSEC-2019-0035"],"url":"https://o3.security/vulnerability/CVE-2020-25576","summary":"Unaligned memory access in rand_core","details":"### Impact\nAffected versions of this crate violated alignment when casting byte slices to integer slices, resulting in undefined behavior. `rand_core::BlockRng::next_u64` and `rand_core::BlockRng::fill_bytes` are affected.\n\n### Patches\nThe flaw was corrected by Ralf Jung and Diggory Hardy for `rand_core >= 0.4.2`.\n\n### Workarounds\nNone.\n\n### References\nSee [Rand's changelog](https://github.com/rust-random/rand/blob/master/rand_core/CHANGELOG.md#050---2019-06-06).\n\n### For more information\nIf you have any questions or comments about this advisory, [open an issue in the Rand repository](https://github.com/rust-random/rand/issues/new/choose).\n\n","published":"2020-09-14T19:15:11.473Z","modified":"2026-08-21T17:13:42.497411Z","cvss":{"score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"epss":{"score":0.01558,"percentile":0.72883,"asOf":"2026-08-23"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"crates.io","name":"rand_core","fixedVersion":"0.4.2"},{"ecosystem":"crates.io","name":"rand_core","fixedVersion":"0.3.1"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://rustsec.org/advisories/RUSTSEC-2019-0035.html"},{"type":"WEB","url":"https://github.com/rust-random/rand/security/advisories/GHSA-mmc9-pwm7-qj5w"},{"type":"PACKAGE","url":"https://github.com/rust-random/rand"},{"type":"WEB","url":"https://github.com/rust-random/rand/blob/master/rand_core/CHANGELOG.md#050---2019-06-06"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-21T17:13:42.497411Z"}}