---
id: RUSTSEC-2026-0398
title: >-
  `Seekable::decompress` sets a `Vec` length beyond its capacity for offsets
  past the end
summary: >-
  `Seekable::decompress` sets a `Vec` length beyond its capacity for offsets
  past the end
severity: none
vendor: zstd-safe
product: zstd-safe
ecosystem: rust
affected:
  - 'zstd-safe >= 7.2.2, < 8.2.0'
patched:
  - zstd-safe 8.2.0
published: '2026-10-16'
updated: '2026-10-26'
sourceUpdated: '2026-10-26T14:00:05.092082939Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/RUSTSEC-2026-0398'
references:
  - url: 'https://crates.io/crates/zstd-safe'
  - url: 'https://rustsec.org/advisories/RUSTSEC-2026-0398.html'
  - url: >-
      https://github.com/gyscos/zstd-rs/commit/80506be743fae2ed0c2fe8b21c374c6a2eab0be7
  - url: 'https://github.com/gyscos/zstd-rs/pull/384'
tags:
  - osv
  - rust
ingestedAt: '2026-10-27T16:20:12.103Z'
---

## Overview

`ZSTD_seekable_decompress` shortens the requested length to the end of the
data without checking that the offset is before it. For an offset past the
end, it returns a wrapped-around length without writing anything, and
`Seekable::decompress` passed that length to `Vec::set_len`.

With the `seekable` feature, whoever supplies the archive, or chooses the
offset, can leave the caller's `Vec<u8>` with a length far beyond its
capacity. Reading it then discloses neighbouring heap memory, and appending
to it corrupts memory. Offsets near `u64::MAX` can also hang the call.

The flaw was corrected by clamping requests to the end of the data, and by
checking every count reported by the C library against the buffer capacity.

## Affected packages

- `zstd-safe >= 7.2.2, < 8.2.0`

## Remediation

Upgrade to a patched release:

- `zstd-safe 8.2.0`