RUSTSEC-2026-0391
Data from an abandoned stream leaks into the next stream on a reused context
The with_context constructors of the stream encoders and decoders used the
borrowed context as it was. When a stream was abandoned on a context, for
example an encoder dropped before finish() after an error, whatever it
left there was carried into the next stream: the input buffered by the
previous encoder (up to 128 KiB, or all of it with zstdmt) became the
start of the next frame, and a decoder returned undelivered output of the
previous stream.
An application reusing one context for data that must stay separate, such as different users' requests, could disclose one user's plaintext to another. Whoever supplies the data can cause the abandonment with invalid input.
The flaw was corrected by resetting the context's session in
with_context.
What each source reports
OSV No score
Data from an abandoned stream leaks into the next stream on a reused context
The with_context constructors of the stream encoders and decoders used the
borrowed context as it was. When a stream was abandoned on a context, for
example an encoder dropped before finish() after an error, whatever it
left there was carried into the next stream: the input buffered by the
previous encoder (up to 128 KiB, or all of it with zstdmt) became the
start of the next frame, and a decoder returned undelivered output of the
previous stream.
An application reusing one context for data that must stay separate, such as different users' requests, could disclose one user's plaintext to another. Whoever supplies the data can cause the abandonment with invalid input.
The flaw was corrected by resetting the context's session in
with_context.
- Record
RUSTSEC-2026-0391- Updated
- 2026-11-02
Affected packages
| Package | Affected | Fixed |
|---|---|---|
zstdcrates.io |
0.13.2 up to 0.13.4, 0.14.0-0 up to 0.14.3 | 0.13.40.14.3 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
RUSTSEC-2026-0391 is a vulnerability with no CVSS score yet in zstd, published October 16, 2026. No source lists public exploit code. Fixed in zstd 0.13.4.