- Reported
-
- Issued
-
- Package
-
zstd
(crates.io)
- Type
-
Vulnerability
- Categories
-
- Keywords
-
#uninitialized-memory
#decompression
#legacy
- References
-
- Patched
-
- Unaffected
-
Description
From 0.4.22 to 0.7.x, the writer behind zstd::stream::write::Decoder set
its output buffer's length to its full capacity before each decompression
call, then to the position the call reported, and only checked for an error
afterwards. When decompression fails inside a legacy (zstd v0.4 to v0.7)
frame, the bundled zstd library reports the output as fully written although
nothing was written, so stale heap memory, up to the buffer size (32 KiB by
default), was passed to the wrapped writer.
Legacy support is enabled by default, and a few bytes of corrupt legacy
frame are enough. Whether this reaches an attacker depends on where the
application sends the decompressed output.
From 0.8.0, the writer uses zstd-safe's buffers, and the same flaw there is
covered by the zstd-safe advisory for it, fixed in zstd-safe 8.2.0.
Advisory available under CC0-1.0
license.