RUSTSEC-2026-0402
Heap buffer overflow in `CCtx::try_clone` on a multithreaded context
- Severity
- Not rated yet
- No source has published a CVSS score yet
- Exploit chance (EPSS)
- —
- No score published
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- —
- Not classified
- Fix
8.2.0- Upgrade zstd-safe to this version or later
Description
CCtx::try_clone (experimental feature, deprecated) copies tables sized
from the context's applied parameters. Starting a multithreaded frame
(zstdmt feature) replaces those parameters with the workers' without
resizing the context's own tables, so after an abandoned single-threaded
frame, the copy wrote up to 512 KiB past a heap allocation, or read past
one. This became reachable with the bundled zstd 1.5.6.
The flaw was corrected by refusing try_clone (and the unsafe
compress_block) once NbWorkers was set on the context.
Affected versions
crates.io
| Package | Vulnerable | Fixed in |
|---|---|---|
| zstd-safe | >= 4.1.4, < 8.2.0 |
8.2.0 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
zstd-safe crates.io → 8.2.0
- cargo
cargo update -p zstd-safe --precise 8.2.0
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| RUSTSEC-2026-0406 Use-after-free when changing a multithreaded context with an unfinished frame | Not rated yet | Also affects zstd-safe |
| RUSTSEC-2026-0405 Out-of-bounds read with an out-of-range `InBuffer::pos` | Not rated yet | Also affects zstd-safe |
| RUSTSEC-2026-0404 Double free in `DCtx::try_clone` | Not rated yet | Also affects zstd-safe |
| RUSTSEC-2026-0403 Uninitialized memory exposed when streaming decompression of a legacy frame fails | Not rated yet | Also affects zstd-safe |
| RUSTSEC-2026-0401 Out-of-bounds read in `train_from_buffer` when sample sizes overflow | Not rated yet | Also affects zstd-safe |
| RUSTSEC-2026-0400 Use-after-free of a dictionary after a one-shot call on a context with an open stream | Not rated yet | Also affects zstd-safe |
| RUSTSEC-2026-0399 Use-after-free through `init_using_cdict` and `init_using_ddict` | Not rated yet | Also affects zstd-safe |
| RUSTSEC-2026-0398 `Seekable::decompress` sets a `Vec` length beyond its capacity for offsets past the end | Not rated yet | Also affects zstd-safe |
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