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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

`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.

Published by the source

16 Oct 2026, 12:00 UTC

Last modified by the source

2 Nov 2026, 09:30 UTC

Source last checked

3 Nov 2026, 06:10 UTC

1. Revision 2 · amended · 3 Nov 2026

   Amended from osv record RUSTSEC-2026-0398

2. Revision 1 · created · 27 Oct 2026

   Published from osv record RUSTSEC-2026-0398

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# Patch Next advisory brief: rustsec-2026-0398

Advisory: `Seekable::decompress` sets a `Vec` length beyond its capacity for offsets past the end
IDs: rustsec-2026-0398
Record: https://patchnext.com/advisories/rustsec-2026-0398 (revision 2, source checked 3 Nov 2026, 06:10 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: zstd-safe 8.2.0, 7.4.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io zstd-safe: affected >= 7.2.2, < 7.4.0; >= 8.0.0-0, < 8.2.0; fixed in 7.4.0, 8.2.0

## Suggested inspection (read-only)
- crates.io zstd-safe: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on zstd-safe.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/RUSTSEC-2026-0398 (OSV record RUSTSEC-2026-0398 lists affected ranges: crates.io zstd-safe >=7.2.2 <8.2.0 (fixed))
- Verified: https://osv.dev/vulnerability/RUSTSEC-2026-0398 (OSV record RUSTSEC-2026-0398 lists affected ranges: crates.io zstd-safe >=7.2.2 =8.0.0-0 <8.2.0 (fixed))

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