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`Seekable::decompress` sets a `Vec` length beyond its capacity for offsets past the end

Type: advisorySources: OSV

`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` 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.

Products
zstd-safe
Affected versions
Not specified
Fixed versions
8.2.0
CVEs
Not specified
Confirmed fixed CVEs
Not specified
Updated in this feed
1 Nov 2026, 14:47 UTC · Revision 1

Source evidence

`Seekable::decompress` sets a `Vec` length beyond its capacity for offsets past the end

core-osv · Original source

Published 16 Oct 2026, 12:00 UTC

`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` 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.

osv:RUSTSEC-2026-0398

zstd-safe

Fixed versions: 8.2.0

Complete source record
{
  "id": "49d6b01fe7c533f0e7833f76580bfa6754ad57ef52ab59ea114b17164251a3e2",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2026-0398",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "`Seekable::decompress` sets a `Vec` length beyond its capacity for offsets past the end",
    "summary": "`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` 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.",
    "evidence": "osv:RUSTSEC-2026-0398",
    "products": [
      {
        "name": {
          "value": "zstd-safe",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "8.2.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "RUSTSEC-2026-0398",
      "aliases": [
        "RUSTSEC-2026-0398"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "7.2.2"
                },
                {
                  "fixed": "8.2.0"
                }
              ]
            }
          ],
          "package": {
            "name": "zstd-safe",
            "purl": "pkg:cargo/zstd-safe",
            "ecosystem": "crates.io"
          },
          "database_specific": {
            "cvss": null,
            "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2026-0398.json",
            "categories": [
              "memory-exposure",
              "memory-corruption"
            ],
            "informational": null
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": [
                "zstd_safe::seekable::AdvancedSeekable::decompress",
                "zstd_safe::seekable::Seekable::decompress"
              ]
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-26T14:00:05.092082939Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/zstd-safe",
        "https://rustsec.org/advisories/RUSTSEC-2026-0398.html",
        "https://github.com/gyscos/zstd-rs/commit/80506be743fae2ed0c2fe8b21c374c6a2eab0be7",
        "https://github.com/gyscos/zstd-rs/pull/384"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 454192,
  "published_at": "2026-10-16T12:00:00+00:00"
}