Zstd safe: Use-after-free of a dictionary after a one-shot call on a context with an open stream
Affects zstd-safeSource GCVE Database
Rated by Threat Radar
- Patch
- Available – fixed in 8.2.0
Data as of 26 Oct 2026, 16:13 UTC
What to do
Upgrade zstd-safe to 8.2.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
crates.iozstd-safepkg:cargo/zstd-safeOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
The one-shot `DCtx` and `CCtx` methods assumed the C library resets the context, but it leaves an open stream as it is. When a stream was left unfinished on a context, a one-shot call such as `decompress_using_dict` could leave the context pointing at the dictionary borrowed for that call, and the next streaming call resumed the stream against it after it was freed: decompressed output then contained freed heap memory. On the compression side, the stream resumed against the one-shot call's buffers. This requires an application to use one context for both streaming and one-shot calls without a reset in between. The flaw was corrected by resetting the session after one-shot calls whenever a stream may be open.