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Advisory record · RUSTSEC-2026-0402

Heap buffer overflow in `CCtx::try_clone` on a multithreaded context

No CVSS score

Published by OSV at 16 Oct 2026, 12:00 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
zstd-safecrates.io>=4.1.4, <7.4.0 || >=8.0.0-0, <8.2.07.4.0, 8.2.0
Identifiers
RUSTSEC-2026-0402
Published
16 Oct 2026
Updated
2 Nov 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Versions of zstd-safe from 4.1.4 before 7.4.0, and from 8.0.0 before 8.2.0, have a heap buffer overflow in CCtx::try_clone when the context was used for a multithreaded frame after an abandoned single-threaded frame. The copy can write up to 512 KiB past a heap allocation or read past one. The source does not describe what an attacker must do to trigger it. Upgrade to zstd-safe 7.4.0 or 8.2.0, or later. The flaw was fixed by refusing try_clone once NbWorkers is set on the context.

Written 3 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

No source has published a CVSS score for this record yet.

  • CISA KEV Not listed.
  • EPSS No score.

Timeline

  1. 31 Oct 2026, 14:24 UTC First seen by agentprime
  2. 31 Oct 2026, 14:24 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.