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Uninitialized memory exposed by write::Decoder on a corrupt legacy frame

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (zstd 0.8.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • crates.io zstd

    Affected
    >= 0.4.22, < 0.8.0
    Fixed in
    0.8.0

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
not scored
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

From 0.4.22 to 0.7.x, the writer behind `zstd::stream::write::Decoder` set its output buffer's length to its full capacity before each decompression call, then to the position the call reported, and only checked for an error afterwards. When decompression fails inside a legacy (zstd v0.4 to v0.7) frame, the bundled zstd library reports the output as fully written although nothing was written, so stale heap memory, up to the buffer size (32 KiB by default), was passed to the wrapped writer. Legacy support is enabled by default, and a few bytes of corrupt legacy frame are enough. Whether this reaches an attacker depends on where the application sends the decompressed output. From 0.8.0, the writer uses zstd-safe's buffers, and the same flaw there is covered by the zstd-safe advisory for it, fixed in zstd-safe 8.2.0.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from osv record RUSTSEC-2026-0392

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: rustsec-2026-0392

Advisory: Uninitialized memory exposed by `write::Decoder` on a corrupt legacy frame
IDs: rustsec-2026-0392
Record: https://patchnext.com/advisories/rustsec-2026-0392 (revision 1, source checked 27 Oct 2026, 06:25 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 0.8.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io zstd: affected >= 0.4.22, < 0.8.0; fixed in 0.8.0

## Suggested inspection (read-only)
- crates.io zstd: 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.
- 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-2026-0392 (OSV record RUSTSEC-2026-0392 lists affected ranges: crates.io zstd >=0.4.22 <0.8.0 (fixed))

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