- Reported
-
- Issued
-
- Package
-
sheets-diff
(crates.io)
- Type
-
Vulnerability
- Categories
-
- Keywords
-
#xlsx
#DoS
#allocation
#cfb
- Aliases
-
- References
-
- CVSS Score
- 5.5
MEDIUM
- CVSS Details
-
- Attack Vector
- Local
- Attack Complexity
- Low
- Privileges Required
- None
- User Interaction
- Required
- Scope
- Unchanged
- Confidentiality Impact
- None
- Integrity Impact
- None
- Availability Impact
- High
- CVSS Vector
- CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
- Patched
-
Description
Affected versions passed caller-supplied bytes to calamine's Xlsx::new without first checking
that they were a ZIP archive. Xlsx::new tests for password protection on its first line, which
parses the input as an OLE/CFB container, and a sector-count field read from the file's own header
reaches Vec::with_capacity without being checked against the file's actual length. A 512-byte input
can therefore request several gigabytes; 9,261,285,372 bytes was measured.
The oversized allocation is always attempted. Whether it aborts depends on what the allocator can
satisfy. On a large host with overcommit the reservation is granted untouched and the call returns
an ordinary "not an xlsx file" error, which looks like a malformed file being correctly rejected.
Under a memory limit the same bytes give memory allocation of N bytes failed and the process
aborts, which is not a Result a caller can handle. Containers with a memory limit, small hosts and
CI runners are where this lands, so testing on a development machine can wrongly suggest the crate is
unaffected.
Every entry point reaches it, not only compare_bytes: the path- and reader-based APIs funnel through
the same internal open. Neither Limits::default() nor Limits::hardened() prevents it, because
max_input_bytes bounds the length of the input while the allocation's size comes from a field
inside it.
Fixed in 3.2.0, which declines input that does not begin with the ZIP magic before the parser sees
it, removing the path rather than bounding it. Callers who cannot upgrade can apply the same check
before calling this crate.
The underlying defect is in calamine, reported there independently as
tafia/calamine#714 and unfixed at the time of
writing. It is reachable from any crate that opens untrusted bytes with Xlsx::new.
Advisory available under CC0-1.0
license.