# RUSTSEC-2026-0317: A 512-byte workbook can provoke a multi-gigabyte allocation and abort the process

> Attackers can cause denial of service by providing a small malicious file that triggers excessive memory allocation in the calamine library.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Sep 2026
- **Also known as:** GHSA-w5x2-6474-pqp4

## What is RUSTSEC-2026-0317?

RUSTSEC-2026-0317 is a denial of service vulnerability in sheets-diff, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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](https://github.com/tafia/calamine/issues/714) and unfixed at the time of
writing. It is reachable from any crate that opens untrusted bytes with `Xlsx::new`.

## Which versions are affected by RUSTSEC-2026-0317?

1 open source package ship an affected version, including sheets-diff.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `sheets-diff` | crates.io | From 0.0.0-0 | 3.2.0 |

## How do I fix RUSTSEC-2026-0317?

Upgrade sheets-diff to 3.2.0 or later.

## Is RUSTSEC-2026-0317 being exploited?

There is no known exploitation of RUSTSEC-2026-0317 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0317 and fix it if it is affected.

What it is: RUSTSEC-2026-0317 is a denial of service vulnerability in sheets-diff, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of RUSTSEC-2026-0317 in the wild and no public exploit code.

Affected packages and fixed versions:
- sheets-diff (crates.io): affected from 0.0.0-0; fixed in 3.2.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/RUSTSEC-2026-0317/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0317/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0317

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0317/
Summaries are generated and may contain mistakes; the official description above is the record.