Findings

RUSTSEC-2026-0344

Decompression bomb in : a tiny input can exhaust memory (OOM)

Published Oct 11, 2026 · updated Oct 13, 2026

A crafted input under 128 KB can force to allocate several gigabytes at once, crashing the process with an out-of-memory condition. Since is a decoder for untrusted input, a single small file is enough to take down anything decoding it. The compressed size of a block was capped at 128 KB, but a compressed block's **decompressed** size was never checked against (RFC 8878). In 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 counter overflow on such a block caused an additional panic.) This is a denial of service only; memory access stays in bounds (no corruption, no RCE). is also built as a dependency of the Rust standard library via ; in the toolchain it is used only to load zstd-compressed debug symbols, so the toolchain-side impact is limited. **Fixed in 0.9.1** (commit ), which enforces the per-block output bound. Upgrade to .