# RUSTSEC-2026-0318: Sending custom to-device messages may panics

> A panic occurs in the Rust encryption library when using IdentityBasedStrategy with recipients lacking cross-signing keys, causing denial of service.

- **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-45pr-7vv7-f64m

## What is RUSTSEC-2026-0318?

RUSTSEC-2026-0318 is a denial of service vulnerability in matrix-sdk-crypto, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Using the `IdentityBasedStrategy` setting when calling
`Device::encrypt_event_raw` or `OlmMachine::encrypt_content_for_devices` may
cause a panic if the recipient does not have cross-signing keys.

## Which versions are affected by RUSTSEC-2026-0318?

1 open source package ship an affected version, including matrix-sdk-crypto.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `matrix-sdk-crypto` | crates.io | From 0.0.0-0 | 0.19.0 |

## How do I fix RUSTSEC-2026-0318?

Upgrade matrix-sdk-crypto to 0.19.0 or later.

## Is RUSTSEC-2026-0318 being exploited?

There is no known exploitation of RUSTSEC-2026-0318 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0318 and fix it if it is affected.

What it is: RUSTSEC-2026-0318 is a denial of service vulnerability in matrix-sdk-crypto, 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-2026-0318 in the wild and no public exploit code.

Affected packages and fixed versions:
- matrix-sdk-crypto (crates.io): affected from 0.0.0-0; fixed in 0.19.0

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-2026-0318/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0318/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0318

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0318/
Summaries are generated and may contain mistakes; the official description above is the record.