PT-2026-125065

Published

2026-10-16

·

Updated

2026-10-16

Description by

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When a multithreaded frame (zstdmt feature, CParameter::NbWorkers) is left unfinished, its jobs may still be running on the worker threads: the C library only waits for them when the next frame starts, or when the context is freed. A session reset makes the context accept changes again in the meantime, so:
  • unloading the dictionary (load dictionary, ref cdict, ref prefix, disable dictionary, init*, or reset with parameters) freed the dictionary a worker was still compressing against;
  • changing NbWorkers made the next frame resize the job table before waiting for the old jobs.
The flaw was corrected by refusing these calls while a multithreaded frame is unfinished. The new CCtx::wait for workers() waits for the workers first.
Vendors
Affected products
Related identifiers
RUSTSEC-2026-0406
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