# h2 unbounded empty DATA frames

Advisory record · `GHSA-q83h-524g-xf6h`

- **Identifiers:** `GHSA-q83h-524g-xf6h` · `RUSTSEC-2026-0258`
- **State:** Confirmed
- **Severity:** No CVSS score
- **Critical:** No
- **Published:** 17 Aug 2026
- **Updated:** 12 Oct 2026
- **Reviewed by a person:** No

[Published by the maintainers](https://github.com/hyperium/hyper/security/advisories/GHSA-q83h-524g-xf6h) · not yet reviewed by GitHub. The hyperium/hyper maintainers published this as a GitHub repository advisory; GitHub’s reviewed advisory replaces it here when it arrives.

Published by the hyperium/hyper maintainers at 17 Aug 2026, 12:00 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `h2` (crates.io): affected `>=0.0.0-0, <0.4.16`; fixed in `0.4.16`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> The h2 package, versions before 0.4.16, accepts and queues empty DATA frames without any limit. An attacker able to send HTTP/2 traffic to a server using the affected version can cause unbounded memory growth when streams are not actively drained, or a panic if the length overflows. Upgrade h2 to version 0.4.16 or later.

Written 3 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

No source has published a CVSS score for this record yet.

- **CISA KEV:** Not listed.
- **EPSS:** No score.

## Timeline

- 17 Aug 2026, 13:29 UTC: [Published by the maintainers as a GitHub repository advisory](https://github.com/hyperium/hyper/security/advisories/GHSA-q83h-524g-xf6h)
- 31 Oct 2026, 14:24 UTC: First seen by agentprime
- 31 Oct 2026, 14:24 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/RUSTSEC-2026-0258)

## Sources

- [GitHub Advisory Database: GHSA-q83h-524g-xf6h](https://github.com/advisories/GHSA-q83h-524g-xf6h)
- [OSV: GHSA-q83h-524g-xf6h](https://osv.dev/vulnerability/GHSA-q83h-524g-xf6h)
- <https://crates.io/crates/h2>
- <https://rustsec.org/advisories/RUSTSEC-2026-0258.html>
- <https://github.com/hyperium/h2/pull/935>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-q83h-524g-xf6h>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-q83h-524g-xf6h/>. Everything for agents: <https://agentprime.io/llms.txt>.