# RUSTSEC-2026-0238: Low-level GCM ignores the operation nonce

> The dcrypt-algorithms library ignores operation nonces in GCM mode, allowing nonce reuse that compromises confidentiality and authenticity, requiring key rotation and data re-encryption.

- **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:** 9 Aug 2026
- **Also known as:** GHSA-h9f2-fgp8-vc4h

## What is RUSTSEC-2026-0238?

RUSTSEC-2026-0238 is a vulnerability in dcrypt-algorithms, published on 9 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In all published versions of `dcrypt-algorithms` before 2.0.0, the low-level
`Gcm` builder required an operation nonce but derived `J0` from the nonce
captured by the original `Gcm` constructor. Multiple operations could therefore
silently reuse a nonce even when callers supplied distinct values, compromising
confidentiality and authenticity under an affected key.

Version 2.0.0 makes `Gcm` key-only and passes the operation nonce through IV
derivation, encryption, and decryption. It also corrects non-96-bit IV
processing, rejects tags shorter than 96 bits, and enforces counter limits.
Applications must upgrade, identify affected keys, rotate them, and re-encrypt
affected data; updating the implementation cannot restore security after nonce
reuse.

## Which versions are affected by RUSTSEC-2026-0238?

1 open source package ship an affected version, including dcrypt-algorithms.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `dcrypt-algorithms` | crates.io | From 0.0.0-0 | 2.0.0 |

## How do I fix RUSTSEC-2026-0238?

Upgrade dcrypt-algorithms to 2.0.0 or later.

## Is RUSTSEC-2026-0238 being exploited?

There is no known exploitation of RUSTSEC-2026-0238 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0238 and fix it if it is affected.

What it is: RUSTSEC-2026-0238 is a vulnerability in dcrypt-algorithms, published on 9 Aug 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-2026-0238 in the wild and no public exploit code.

Affected packages and fixed versions:
- dcrypt-algorithms (crates.io): affected from 0.0.0-0; fixed in 2.0.0

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-2026-0238/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0238/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0238

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0238/
Summaries are generated and may contain mistakes; the official description above is the record.