{"id":"RUSTSEC-2026-0344","summary":"Decompression bomb in `ruzstd`: a tiny input can exhaust memory (OOM)","details":"A crafted `.zst` input under 128 KB can force `ruzstd` to allocate several gigabytes at once, crashing the process with an out-of-memory condition. Since `ruzstd` is a decoder for untrusted input, a single small file is enough to take down anything decoding it.\n\nThe compressed size of a block was capped at 128 KB, but a compressed block's **decompressed** size was never checked against `Block_Maximum_Size = min(Window_Size, 128 KiB)` (RFC 8878). In `execute_sequences` the output was built with no running bound and no flush between blocks, so one block could expand to gigabytes — bypassing both the configured window-size limit and the block-by-block streaming that would otherwise release memory. (A related `u32` counter overflow on such a block caused an additional panic.)\n\nThis is a denial of service only; memory access stays in bounds (no corruption, no RCE).\n\n`ruzstd` is also built as a dependency of the Rust standard library via `rustc-dep-of-std`; in the toolchain it is used only to load zstd-compressed debug symbols, so the toolchain-side impact is limited.\n\n**Fixed in 0.9.1** (commit `d3907c9`), which enforces the per-block output bound. Upgrade to `ruzstd \u003e= 0.9.1`.","modified":"2026-10-13T10:45:04.080993335Z","published":"2026-10-11T12:00:00Z","database_specific":{"license":"CC0-1.0"},"references":[{"type":"PACKAGE","url":"https://crates.io/crates/ruzstd"},{"type":"ADVISORY","url":"https://rustsec.org/advisories/RUSTSEC-2026-0344.html"},{"type":"WEB","url":"https://github.com/KillingSpark/zstd-rs/commit/d3907c960ca4a1aa44cc38340137c5679dd98f5a"}],"affected":[{"package":{"name":"ruzstd","ecosystem":"crates.io","purl":"pkg:cargo/ruzstd"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.0.0-0"},{"fixed":"0.9.1"}]}],"ecosystem_specific":{"affects":{"arch":[],"os":[],"functions":[]},"affected_functions":null},"database_specific":{"informational":null,"categories":["denial-of-service"],"cvss":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2026-0344.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:N/A:H"}]}