Use-after-free of a dictionary after a one-shot call on a context with an open stream

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.

Source published

16 Oct 2026 12:00:00 UTC

Source modified

26 Oct 2026 14:00:05 UTC

Observed here

26 Oct 2026 14:35:44 UTC

Source terms

OSV · upstream source license applies

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