# RUSTSEC-2026-0287: cosmian_kyber is unmaintained

> The unmaintained cosmian_kyber library contains broken constant-time code, potentially allowing side-channel attacks against cryptographic operations.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 17 Sep 2026

## What is RUSTSEC-2026-0287?

RUSTSEC-2026-0287 is a vulnerability in cosmian_kyber, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

`cosmian_kyber` is a fork of `Argyle-Software/kyber` that has seen no maintainer
activity. It inherits the fork parent's broken AVX2 constant-time code, and the
open fix pull request (Cosmian/kyber#6) has gone unanswered.

Recommended alternatives:

- [aws-lc-rs](https://crates.io/crates/aws-lc-rs)
- [graviola](https://crates.io/crates/graviola)

## Which versions are affected by RUSTSEC-2026-0287?

1 open source package ship an affected version, including cosmian_kyber.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `cosmian_kyber` | crates.io | From 0.0.0-0 | None |

## How do I fix RUSTSEC-2026-0287?

No fix has been published for RUSTSEC-2026-0287 yet. Limit exposure of the affected software until one is available.

## Is RUSTSEC-2026-0287 being exploited?

There is no known exploitation of RUSTSEC-2026-0287 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0287 and fix it if it is affected.

What it is: RUSTSEC-2026-0287 is a vulnerability in cosmian_kyber, published on 17 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-2026-0287 in the wild and no public exploit code.

Affected packages and fixed versions:
- cosmian_kyber (crates.io): affected from 0.0.0-0; no fix listed

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-2026-0287/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0287/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0287

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0287/
Summaries are generated and may contain mistakes; the official description above is the record.