# RUSTSEC-2026-0258: h2 unbounded empty DATA frames

> Attackers can cause denial of service via unbounded memory usage or panics by sending excessive empty HTTP/2 DATA frames to applications using the h2 crate.

- **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:** 17 Aug 2026
- **Also known as:** GHSA-q83h-524g-xf6h

## What is RUSTSEC-2026-0258?

RUSTSEC-2026-0258 is a denial of service vulnerability in h2, published on 17 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The h2 crate, used internally by hyper, had a flaw that would accept and queue empty DATA frames without limit.
If streams were not actively drained, this could lead to unbounded memory usage, or a panic if the length overflows.

Low severity.

Patched in v0.4.16.

## Which versions are affected by RUSTSEC-2026-0258?

1 open source package ship an affected version, including h2.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `h2` | crates.io | From 0.0.0-0 | 0.4.16 |

## How do I fix RUSTSEC-2026-0258?

Upgrade h2 to 0.4.16 or later.

## Is RUSTSEC-2026-0258 being exploited?

There is no known exploitation of RUSTSEC-2026-0258 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0258 and fix it if it is affected.

What it is: RUSTSEC-2026-0258 is a denial of service vulnerability in h2, published on 17 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-2026-0258 in the wild and no public exploit code.

Affected packages and fixed versions:
- h2 (crates.io): affected from 0.0.0-0; fixed in 0.4.16

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-2026-0258/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0258/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0258

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0258/
Summaries are generated and may contain mistakes; the official description above is the record.